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@@ -1,455 +1,459 b'' | |||
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1 | 1 | # worker.py - master-slave parallelism support |
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2 | 2 | # |
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3 | 3 | # Copyright 2013 Facebook, Inc. |
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4 | 4 | # |
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5 | 5 | # This software may be used and distributed according to the terms of the |
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6 | 6 | # GNU General Public License version 2 or any later version. |
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7 | 7 | |
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8 | 8 | |
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9 | 9 | import errno |
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10 | 10 | import os |
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11 | 11 | import pickle |
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12 | 12 | import signal |
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13 | 13 | import sys |
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14 | 14 | import threading |
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15 | 15 | import time |
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16 | 16 | |
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17 | 17 | try: |
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18 | 18 | import selectors |
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19 | 19 | |
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20 | 20 | selectors.BaseSelector |
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21 | 21 | except ImportError: |
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22 | 22 | from .thirdparty import selectors2 as selectors |
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23 | 23 | |
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24 | 24 | from .i18n import _ |
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25 | 25 | from . import ( |
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26 | 26 | encoding, |
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27 | 27 | error, |
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28 | 28 | pycompat, |
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29 | 29 | scmutil, |
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30 | 30 | ) |
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31 | 31 | |
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32 | 32 | |
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33 | 33 | def countcpus(): |
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34 | 34 | '''try to count the number of CPUs on the system''' |
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35 | 35 | |
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36 | 36 | # posix |
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37 | 37 | try: |
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38 | 38 | n = int(os.sysconf('SC_NPROCESSORS_ONLN')) |
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39 | 39 | if n > 0: |
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40 | 40 | return n |
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41 | 41 | except (AttributeError, ValueError): |
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42 | 42 | pass |
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43 | 43 | |
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44 | 44 | # windows |
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45 | 45 | try: |
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46 | 46 | n = int(encoding.environ[b'NUMBER_OF_PROCESSORS']) |
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47 | 47 | if n > 0: |
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48 | 48 | return n |
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49 | 49 | except (KeyError, ValueError): |
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50 | 50 | pass |
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51 | 51 | |
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52 | 52 | return 1 |
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53 | 53 | |
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54 | 54 | |
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55 | 55 | def _numworkers(ui): |
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56 | 56 | s = ui.config(b'worker', b'numcpus') |
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57 | 57 | if s: |
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58 | 58 | try: |
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59 | 59 | n = int(s) |
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60 | 60 | if n >= 1: |
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61 | 61 | return n |
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62 | 62 | except ValueError: |
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63 | 63 | raise error.Abort(_(b'number of cpus must be an integer')) |
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64 | 64 | return min(max(countcpus(), 4), 32) |
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65 | 65 | |
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66 | 66 | |
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67 | 67 | def ismainthread(): |
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68 | 68 | return threading.current_thread() == threading.main_thread() |
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69 | 69 | |
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70 | 70 | |
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71 | 71 | class _blockingreader(object): |
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72 | 72 | def __init__(self, wrapped): |
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73 | 73 | self._wrapped = wrapped |
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74 | 74 | |
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75 | 75 | # Do NOT implement readinto() by making it delegate to |
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76 | 76 | # _wrapped.readinto(), since that is unbuffered. The unpickler is fine |
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77 | 77 | # with just read() and readline(), so we don't need to implement it. |
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78 | 78 | |
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79 | 79 | def readline(self): |
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80 | 80 | return self._wrapped.readline() |
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81 | 81 | |
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82 | 82 | # issue multiple reads until size is fulfilled |
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83 | 83 | def read(self, size=-1): |
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84 | 84 | if size < 0: |
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85 | 85 | return self._wrapped.readall() |
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86 | 86 | |
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87 | 87 | buf = bytearray(size) |
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88 | 88 | view = memoryview(buf) |
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89 | 89 | pos = 0 |
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90 | 90 | |
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91 | 91 | while pos < size: |
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92 | 92 | ret = self._wrapped.readinto(view[pos:]) |
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93 | 93 | if not ret: |
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94 | 94 | break |
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95 | 95 | pos += ret |
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96 | 96 | |
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97 | 97 | del view |
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98 | 98 | del buf[pos:] |
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99 | 99 | return bytes(buf) |
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100 | 100 | |
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101 | 101 | |
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102 | 102 | if pycompat.isposix or pycompat.iswindows: |
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103 | 103 | _STARTUP_COST = 0.01 |
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104 | 104 | # The Windows worker is thread based. If tasks are CPU bound, threads |
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105 | 105 | # in the presence of the GIL result in excessive context switching and |
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106 | 106 | # this overhead can slow down execution. |
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107 | 107 | _DISALLOW_THREAD_UNSAFE = pycompat.iswindows |
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108 | 108 | else: |
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109 | 109 | _STARTUP_COST = 1e30 |
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110 | 110 | _DISALLOW_THREAD_UNSAFE = False |
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111 | 111 | |
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112 | 112 | |
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113 | 113 | def worthwhile(ui, costperop, nops, threadsafe=True): |
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114 | 114 | """try to determine whether the benefit of multiple processes can |
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115 | 115 | outweigh the cost of starting them""" |
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116 | 116 | |
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117 | 117 | if not threadsafe and _DISALLOW_THREAD_UNSAFE: |
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118 | 118 | return False |
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119 | 119 | |
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120 | 120 | linear = costperop * nops |
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121 | 121 | workers = _numworkers(ui) |
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122 | 122 | benefit = linear - (_STARTUP_COST * workers + linear / workers) |
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123 | 123 | return benefit >= 0.15 |
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124 | 124 | |
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125 | 125 | |
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126 | 126 | def worker( |
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127 | 127 | ui, costperarg, func, staticargs, args, hasretval=False, threadsafe=True |
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128 | 128 | ): |
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129 | 129 | """run a function, possibly in parallel in multiple worker |
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130 | 130 | processes. |
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131 | 131 | |
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132 | 132 | returns a progress iterator |
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133 | 133 | |
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134 | 134 | costperarg - cost of a single task |
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135 | 135 | |
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136 | 136 | func - function to run. It is expected to return a progress iterator. |
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137 | 137 | |
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138 | 138 | staticargs - arguments to pass to every invocation of the function |
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139 | 139 | |
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140 | 140 | args - arguments to split into chunks, to pass to individual |
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141 | 141 | workers |
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142 | 142 | |
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143 | 143 | hasretval - when True, func and the current function return an progress |
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144 | 144 | iterator then a dict (encoded as an iterator that yield many (False, ..) |
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145 | 145 | then a (True, dict)). The dicts are joined in some arbitrary order, so |
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146 | 146 | overlapping keys are a bad idea. |
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147 | 147 | |
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148 | 148 | threadsafe - whether work items are thread safe and can be executed using |
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149 | 149 | a thread-based worker. Should be disabled for CPU heavy tasks that don't |
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150 | 150 | release the GIL. |
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151 | 151 | """ |
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152 | 152 | enabled = ui.configbool(b'worker', b'enabled') |
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153 | 153 | if enabled and _platformworker is _posixworker and not ismainthread(): |
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154 | 154 | # The POSIX worker has to install a handler for SIGCHLD. |
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155 | 155 | # Python up to 3.9 only allows this in the main thread. |
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156 | 156 | enabled = False |
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157 | 157 | |
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158 | 158 | if enabled and worthwhile(ui, costperarg, len(args), threadsafe=threadsafe): |
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159 | 159 | return _platformworker(ui, func, staticargs, args, hasretval) |
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160 | 160 | return func(*staticargs + (args,)) |
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161 | 161 | |
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162 | 162 | |
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163 | 163 | def _posixworker(ui, func, staticargs, args, hasretval): |
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164 | 164 | workers = _numworkers(ui) |
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165 | 165 | oldhandler = signal.getsignal(signal.SIGINT) |
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166 | 166 | signal.signal(signal.SIGINT, signal.SIG_IGN) |
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167 | 167 | pids, problem = set(), [0] |
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168 | 168 | |
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169 | 169 | def killworkers(): |
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170 | 170 | # unregister SIGCHLD handler as all children will be killed. This |
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171 | 171 | # function shouldn't be interrupted by another SIGCHLD; otherwise pids |
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172 | 172 | # could be updated while iterating, which would cause inconsistency. |
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173 | 173 | signal.signal(signal.SIGCHLD, oldchldhandler) |
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174 | 174 | # if one worker bails, there's no good reason to wait for the rest |
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175 | 175 | for p in pids: |
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176 | 176 | try: |
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177 | 177 | os.kill(p, signal.SIGTERM) |
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178 | 178 | except OSError as err: |
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179 | 179 | if err.errno != errno.ESRCH: |
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180 | 180 | raise |
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181 | 181 | |
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182 | 182 | def waitforworkers(blocking=True): |
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183 | 183 | for pid in pids.copy(): |
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184 | 184 | p = st = 0 |
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185 | 185 | while True: |
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186 | 186 | try: |
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187 | 187 | p, st = os.waitpid(pid, (0 if blocking else os.WNOHANG)) |
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188 | 188 | break |
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189 | 189 | except OSError as e: |
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190 | 190 | if e.errno == errno.EINTR: |
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191 | 191 | continue |
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192 | 192 | elif e.errno == errno.ECHILD: |
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193 | 193 | # child would already be reaped, but pids yet been |
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194 | 194 | # updated (maybe interrupted just after waitpid) |
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195 | 195 | pids.discard(pid) |
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196 | 196 | break |
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197 | 197 | else: |
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198 | 198 | raise |
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199 | 199 | if not p: |
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200 | 200 | # skip subsequent steps, because child process should |
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201 | 201 | # be still running in this case |
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202 | 202 | continue |
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203 | 203 | pids.discard(p) |
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204 | 204 | st = _exitstatus(st) |
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205 | 205 | if st and not problem[0]: |
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206 | 206 | problem[0] = st |
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207 | 207 | |
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208 | 208 | def sigchldhandler(signum, frame): |
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209 | 209 | waitforworkers(blocking=False) |
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210 | 210 | if problem[0]: |
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211 | 211 | killworkers() |
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212 | 212 | |
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213 | 213 | oldchldhandler = signal.signal(signal.SIGCHLD, sigchldhandler) |
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214 | 214 | ui.flush() |
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215 | 215 | parentpid = os.getpid() |
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216 | 216 | pipes = [] |
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217 | 217 | retval = {} |
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218 | 218 | for pargs in partition(args, min(workers, len(args))): |
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219 | 219 | # Every worker gets its own pipe to send results on, so we don't have to |
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220 | 220 | # implement atomic writes larger than PIPE_BUF. Each forked process has |
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221 | 221 | # its own pipe's descriptors in the local variables, and the parent |
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222 | 222 | # process has the full list of pipe descriptors (and it doesn't really |
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223 | 223 | # care what order they're in). |
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224 | 224 | rfd, wfd = os.pipe() |
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225 | 225 | pipes.append((rfd, wfd)) |
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226 | 226 | # make sure we use os._exit in all worker code paths. otherwise the |
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227 | 227 | # worker may do some clean-ups which could cause surprises like |
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228 | 228 | # deadlock. see sshpeer.cleanup for example. |
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229 | 229 | # override error handling *before* fork. this is necessary because |
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230 | 230 | # exception (signal) may arrive after fork, before "pid =" assignment |
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231 | 231 | # completes, and other exception handler (dispatch.py) can lead to |
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232 | 232 | # unexpected code path without os._exit. |
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233 | 233 | ret = -1 |
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234 | 234 | try: |
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235 | 235 | pid = os.fork() |
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236 | 236 | if pid == 0: |
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237 | 237 | signal.signal(signal.SIGINT, oldhandler) |
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238 | 238 | signal.signal(signal.SIGCHLD, oldchldhandler) |
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239 | 239 | |
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240 | 240 | def workerfunc(): |
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241 | 241 | for r, w in pipes[:-1]: |
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242 | 242 | os.close(r) |
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243 | 243 | os.close(w) |
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244 | 244 | os.close(rfd) |
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245 | 245 | for result in func(*(staticargs + (pargs,))): |
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246 | 246 | os.write(wfd, pickle.dumps(result)) |
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247 | 247 | return 0 |
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248 | 248 | |
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249 | 249 | ret = scmutil.callcatch(ui, workerfunc) |
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250 | 250 | except: # parent re-raises, child never returns |
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251 | 251 | if os.getpid() == parentpid: |
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252 | 252 | raise |
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253 | 253 | exctype = sys.exc_info()[0] |
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254 | 254 | force = not issubclass(exctype, KeyboardInterrupt) |
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255 | 255 | ui.traceback(force=force) |
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256 | 256 | finally: |
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257 | 257 | if os.getpid() != parentpid: |
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258 | 258 | try: |
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259 | 259 | ui.flush() |
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260 | 260 | except: # never returns, no re-raises |
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261 | 261 | pass |
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262 | 262 | finally: |
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263 | 263 | os._exit(ret & 255) |
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264 | 264 | pids.add(pid) |
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265 | 265 | selector = selectors.DefaultSelector() |
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266 | 266 | for rfd, wfd in pipes: |
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267 | 267 | os.close(wfd) |
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268 | 268 | selector.register(os.fdopen(rfd, 'rb', 0), selectors.EVENT_READ) |
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269 | 269 | |
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270 | 270 | def cleanup(): |
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271 | 271 | signal.signal(signal.SIGINT, oldhandler) |
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272 | 272 | waitforworkers() |
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273 | 273 | signal.signal(signal.SIGCHLD, oldchldhandler) |
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274 | 274 | selector.close() |
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275 | 275 | return problem[0] |
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276 | 276 | |
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277 | 277 | try: |
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278 | 278 | openpipes = len(pipes) |
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279 | 279 | while openpipes > 0: |
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280 | 280 | for key, events in selector.select(): |
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281 | 281 | try: |
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282 | # The pytype error likely goes away on a modern version of | |
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283 | # pytype having a modern typeshed snapshot. | |
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284 | # pytype: disable=wrong-arg-types | |
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282 | 285 | res = pickle.load(_blockingreader(key.fileobj)) |
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286 | # pytype: enable=wrong-arg-types | |
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283 | 287 | if hasretval and res[0]: |
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284 | 288 | retval.update(res[1]) |
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285 | 289 | else: |
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286 | 290 | yield res |
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287 | 291 | except EOFError: |
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288 | 292 | selector.unregister(key.fileobj) |
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289 | 293 | key.fileobj.close() |
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290 | 294 | openpipes -= 1 |
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291 | 295 | except IOError as e: |
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292 | 296 | if e.errno == errno.EINTR: |
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293 | 297 | continue |
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294 | 298 | raise |
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295 | 299 | except: # re-raises |
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296 | 300 | killworkers() |
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297 | 301 | cleanup() |
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298 | 302 | raise |
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299 | 303 | status = cleanup() |
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300 | 304 | if status: |
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301 | 305 | if status < 0: |
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302 | 306 | os.kill(os.getpid(), -status) |
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303 | 307 | raise error.WorkerError(status) |
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304 | 308 | if hasretval: |
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305 | 309 | yield True, retval |
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306 | 310 | |
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307 | 311 | |
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308 | 312 | def _posixexitstatus(code): |
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309 | 313 | """convert a posix exit status into the same form returned by |
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310 | 314 | os.spawnv |
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311 | 315 | |
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312 | 316 | returns None if the process was stopped instead of exiting""" |
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313 | 317 | if os.WIFEXITED(code): |
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314 | 318 | return os.WEXITSTATUS(code) |
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315 | 319 | elif os.WIFSIGNALED(code): |
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316 | 320 | return -(os.WTERMSIG(code)) |
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317 | 321 | |
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318 | 322 | |
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319 | 323 | def _windowsworker(ui, func, staticargs, args, hasretval): |
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320 | 324 | class Worker(threading.Thread): |
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321 | 325 | def __init__( |
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322 | 326 | self, taskqueue, resultqueue, func, staticargs, *args, **kwargs |
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323 | 327 | ): |
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324 | 328 | threading.Thread.__init__(self, *args, **kwargs) |
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325 | 329 | self._taskqueue = taskqueue |
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326 | 330 | self._resultqueue = resultqueue |
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327 | 331 | self._func = func |
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328 | 332 | self._staticargs = staticargs |
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329 | 333 | self._interrupted = False |
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330 | 334 | self.daemon = True |
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331 | 335 | self.exception = None |
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332 | 336 | |
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333 | 337 | def interrupt(self): |
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334 | 338 | self._interrupted = True |
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335 | 339 | |
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336 | 340 | def run(self): |
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337 | 341 | try: |
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338 | 342 | while not self._taskqueue.empty(): |
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339 | 343 | try: |
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340 | 344 | args = self._taskqueue.get_nowait() |
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341 | 345 | for res in self._func(*self._staticargs + (args,)): |
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342 | 346 | self._resultqueue.put(res) |
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343 | 347 | # threading doesn't provide a native way to |
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344 | 348 | # interrupt execution. handle it manually at every |
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345 | 349 | # iteration. |
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346 | 350 | if self._interrupted: |
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347 | 351 | return |
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348 | 352 | except pycompat.queue.Empty: |
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349 | 353 | break |
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350 | 354 | except Exception as e: |
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351 | 355 | # store the exception such that the main thread can resurface |
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352 | 356 | # it as if the func was running without workers. |
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353 | 357 | self.exception = e |
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354 | 358 | raise |
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355 | 359 | |
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356 | 360 | threads = [] |
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357 | 361 | |
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358 | 362 | def trykillworkers(): |
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359 | 363 | # Allow up to 1 second to clean worker threads nicely |
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360 | 364 | cleanupend = time.time() + 1 |
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361 | 365 | for t in threads: |
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362 | 366 | t.interrupt() |
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363 | 367 | for t in threads: |
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364 | 368 | remainingtime = cleanupend - time.time() |
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365 | 369 | t.join(remainingtime) |
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366 | 370 | if t.is_alive(): |
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367 | 371 | # pass over the workers joining failure. it is more |
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368 | 372 | # important to surface the inital exception than the |
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369 | 373 | # fact that one of workers may be processing a large |
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370 | 374 | # task and does not get to handle the interruption. |
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371 | 375 | ui.warn( |
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372 | 376 | _( |
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373 | 377 | b"failed to kill worker threads while " |
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374 | 378 | b"handling an exception\n" |
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375 | 379 | ) |
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376 | 380 | ) |
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377 | 381 | return |
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378 | 382 | |
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379 | 383 | workers = _numworkers(ui) |
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380 | 384 | resultqueue = pycompat.queue.Queue() |
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381 | 385 | taskqueue = pycompat.queue.Queue() |
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382 | 386 | retval = {} |
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383 | 387 | # partition work to more pieces than workers to minimize the chance |
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384 | 388 | # of uneven distribution of large tasks between the workers |
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385 | 389 | for pargs in partition(args, workers * 20): |
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386 | 390 | taskqueue.put(pargs) |
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387 | 391 | for _i in range(workers): |
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388 | 392 | t = Worker(taskqueue, resultqueue, func, staticargs) |
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389 | 393 | threads.append(t) |
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390 | 394 | t.start() |
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391 | 395 | try: |
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392 | 396 | while len(threads) > 0: |
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393 | 397 | while not resultqueue.empty(): |
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394 | 398 | res = resultqueue.get() |
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395 | 399 | if hasretval and res[0]: |
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396 | 400 | retval.update(res[1]) |
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397 | 401 | else: |
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398 | 402 | yield res |
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399 | 403 | threads[0].join(0.05) |
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400 | 404 | finishedthreads = [_t for _t in threads if not _t.is_alive()] |
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401 | 405 | for t in finishedthreads: |
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402 | 406 | if t.exception is not None: |
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403 | 407 | raise t.exception |
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404 | 408 | threads.remove(t) |
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405 | 409 | except (Exception, KeyboardInterrupt): # re-raises |
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406 | 410 | trykillworkers() |
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407 | 411 | raise |
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408 | 412 | while not resultqueue.empty(): |
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409 | 413 | res = resultqueue.get() |
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410 | 414 | if hasretval and res[0]: |
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411 | 415 | retval.update(res[1]) |
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412 | 416 | else: |
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413 | 417 | yield res |
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414 | 418 | if hasretval: |
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415 | 419 | yield True, retval |
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416 | 420 | |
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417 | 421 | |
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418 | 422 | if pycompat.iswindows: |
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419 | 423 | _platformworker = _windowsworker |
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420 | 424 | else: |
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421 | 425 | _platformworker = _posixworker |
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422 | 426 | _exitstatus = _posixexitstatus |
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423 | 427 | |
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424 | 428 | |
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425 | 429 | def partition(lst, nslices): |
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426 | 430 | """partition a list into N slices of roughly equal size |
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427 | 431 | |
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428 | 432 | The current strategy takes every Nth element from the input. If |
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429 | 433 | we ever write workers that need to preserve grouping in input |
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430 | 434 | we should consider allowing callers to specify a partition strategy. |
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431 | 435 | |
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432 | 436 | olivia is not a fan of this partitioning strategy when files are involved. |
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433 | 437 | In his words: |
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434 | 438 | |
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435 | 439 | Single-threaded Mercurial makes a point of creating and visiting |
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436 | 440 | files in a fixed order (alphabetical). When creating files in order, |
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437 | 441 | a typical filesystem is likely to allocate them on nearby regions on |
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438 | 442 | disk. Thus, when revisiting in the same order, locality is maximized |
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439 | 443 | and various forms of OS and disk-level caching and read-ahead get a |
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440 | 444 | chance to work. |
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441 | 445 | |
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442 | 446 | This effect can be quite significant on spinning disks. I discovered it |
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443 | 447 | circa Mercurial v0.4 when revlogs were named by hashes of filenames. |
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444 | 448 | Tarring a repo and copying it to another disk effectively randomized |
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445 | 449 | the revlog ordering on disk by sorting the revlogs by hash and suddenly |
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446 | 450 | performance of my kernel checkout benchmark dropped by ~10x because the |
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447 | 451 | "working set" of sectors visited no longer fit in the drive's cache and |
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448 | 452 | the workload switched from streaming to random I/O. |
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449 | 453 | |
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450 | 454 | What we should really be doing is have workers read filenames from a |
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451 | 455 | ordered queue. This preserves locality and also keeps any worker from |
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452 | 456 | getting more than one file out of balance. |
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453 | 457 | """ |
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454 | 458 | for i in range(nslices): |
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455 | 459 | yield lst[i::nslices] |
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