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@@ -1,203 +1,204 b'' | |||||
1 | # worker.py - master-slave parallelism support |
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1 | # worker.py - master-slave parallelism support | |
2 | # |
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2 | # | |
3 | # Copyright 2013 Facebook, Inc. |
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3 | # Copyright 2013 Facebook, Inc. | |
4 | # |
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4 | # | |
5 | # This software may be used and distributed according to the terms of the |
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5 | # This software may be used and distributed according to the terms of the | |
6 | # GNU General Public License version 2 or any later version. |
|
6 | # GNU General Public License version 2 or any later version. | |
7 |
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7 | |||
8 | from __future__ import absolute_import |
|
8 | from __future__ import absolute_import | |
9 |
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9 | |||
10 | import errno |
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10 | import errno | |
11 | import os |
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11 | import os | |
12 | import signal |
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12 | import signal | |
13 | import sys |
|
13 | import sys | |
14 |
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14 | |||
15 | from .i18n import _ |
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15 | from .i18n import _ | |
16 | from . import ( |
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16 | from . import ( | |
17 | error, |
|
17 | error, | |
18 | util, |
|
18 | util, | |
19 | ) |
|
19 | ) | |
20 |
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20 | |||
21 | def countcpus(): |
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21 | def countcpus(): | |
22 | '''try to count the number of CPUs on the system''' |
|
22 | '''try to count the number of CPUs on the system''' | |
23 |
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23 | |||
24 | # posix |
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24 | # posix | |
25 | try: |
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25 | try: | |
26 | n = int(os.sysconf('SC_NPROCESSORS_ONLN')) |
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26 | n = int(os.sysconf('SC_NPROCESSORS_ONLN')) | |
27 | if n > 0: |
|
27 | if n > 0: | |
28 | return n |
|
28 | return n | |
29 | except (AttributeError, ValueError): |
|
29 | except (AttributeError, ValueError): | |
30 | pass |
|
30 | pass | |
31 |
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31 | |||
32 | # windows |
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32 | # windows | |
33 | try: |
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33 | try: | |
34 | n = int(os.environ['NUMBER_OF_PROCESSORS']) |
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34 | n = int(os.environ['NUMBER_OF_PROCESSORS']) | |
35 | if n > 0: |
|
35 | if n > 0: | |
36 | return n |
|
36 | return n | |
37 | except (KeyError, ValueError): |
|
37 | except (KeyError, ValueError): | |
38 | pass |
|
38 | pass | |
39 |
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39 | |||
40 | return 1 |
|
40 | return 1 | |
41 |
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41 | |||
42 | def _numworkers(ui): |
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42 | def _numworkers(ui): | |
43 | s = ui.config('worker', 'numcpus') |
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43 | s = ui.config('worker', 'numcpus') | |
44 | if s: |
|
44 | if s: | |
45 | try: |
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45 | try: | |
46 | n = int(s) |
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46 | n = int(s) | |
47 | if n >= 1: |
|
47 | if n >= 1: | |
48 | return n |
|
48 | return n | |
49 | except ValueError: |
|
49 | except ValueError: | |
50 | raise error.Abort(_('number of cpus must be an integer')) |
|
50 | raise error.Abort(_('number of cpus must be an integer')) | |
51 | return min(max(countcpus(), 4), 32) |
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51 | return min(max(countcpus(), 4), 32) | |
52 |
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52 | |||
53 | if os.name == 'posix': |
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53 | if os.name == 'posix': | |
54 | _startupcost = 0.01 |
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54 | _startupcost = 0.01 | |
55 | else: |
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55 | else: | |
56 | _startupcost = 1e30 |
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56 | _startupcost = 1e30 | |
57 |
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57 | |||
58 | def worthwhile(ui, costperop, nops): |
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58 | def worthwhile(ui, costperop, nops): | |
59 | '''try to determine whether the benefit of multiple processes can |
|
59 | '''try to determine whether the benefit of multiple processes can | |
60 | outweigh the cost of starting them''' |
|
60 | outweigh the cost of starting them''' | |
61 | linear = costperop * nops |
|
61 | linear = costperop * nops | |
62 | workers = _numworkers(ui) |
|
62 | workers = _numworkers(ui) | |
63 | benefit = linear - (_startupcost * workers + linear / workers) |
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63 | benefit = linear - (_startupcost * workers + linear / workers) | |
64 | return benefit >= 0.15 |
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64 | return benefit >= 0.15 | |
65 |
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65 | |||
66 | def worker(ui, costperarg, func, staticargs, args): |
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66 | def worker(ui, costperarg, func, staticargs, args): | |
67 | '''run a function, possibly in parallel in multiple worker |
|
67 | '''run a function, possibly in parallel in multiple worker | |
68 | processes. |
|
68 | processes. | |
69 |
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69 | |||
70 | returns a progress iterator |
|
70 | returns a progress iterator | |
71 |
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71 | |||
72 | costperarg - cost of a single task |
|
72 | costperarg - cost of a single task | |
73 |
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73 | |||
74 | func - function to run |
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74 | func - function to run | |
75 |
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75 | |||
76 | staticargs - arguments to pass to every invocation of the function |
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76 | staticargs - arguments to pass to every invocation of the function | |
77 |
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77 | |||
78 | args - arguments to split into chunks, to pass to individual |
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78 | args - arguments to split into chunks, to pass to individual | |
79 | workers |
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79 | workers | |
80 | ''' |
|
80 | ''' | |
81 | if worthwhile(ui, costperarg, len(args)): |
|
81 | if worthwhile(ui, costperarg, len(args)): | |
82 | return _platformworker(ui, func, staticargs, args) |
|
82 | return _platformworker(ui, func, staticargs, args) | |
83 | return func(*staticargs + (args,)) |
|
83 | return func(*staticargs + (args,)) | |
84 |
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84 | |||
85 | def _posixworker(ui, func, staticargs, args): |
|
85 | def _posixworker(ui, func, staticargs, args): | |
86 | rfd, wfd = os.pipe() |
|
86 | rfd, wfd = os.pipe() | |
87 | workers = _numworkers(ui) |
|
87 | workers = _numworkers(ui) | |
88 | oldhandler = signal.getsignal(signal.SIGINT) |
|
88 | oldhandler = signal.getsignal(signal.SIGINT) | |
89 | signal.signal(signal.SIGINT, signal.SIG_IGN) |
|
89 | signal.signal(signal.SIGINT, signal.SIG_IGN) | |
90 | pids, problem = set(), [0] |
|
90 | pids, problem = set(), [0] | |
91 | def killworkers(): |
|
91 | def killworkers(): | |
92 | # if one worker bails, there's no good reason to wait for the rest |
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92 | # if one worker bails, there's no good reason to wait for the rest | |
93 | for p in pids: |
|
93 | for p in pids: | |
94 | try: |
|
94 | try: | |
95 | os.kill(p, signal.SIGTERM) |
|
95 | os.kill(p, signal.SIGTERM) | |
96 | except OSError as err: |
|
96 | except OSError as err: | |
97 | if err.errno != errno.ESRCH: |
|
97 | if err.errno != errno.ESRCH: | |
98 | raise |
|
98 | raise | |
99 | def waitforworkers(blocking=True): |
|
99 | def waitforworkers(blocking=True): | |
100 | for pid in pids.copy(): |
|
100 | for pid in pids.copy(): | |
101 | p = st = 0 |
|
101 | p = st = 0 | |
102 | while True: |
|
102 | while True: | |
103 | try: |
|
103 | try: | |
104 | p, st = os.waitpid(pid, (0 if blocking else os.WNOHANG)) |
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104 | p, st = os.waitpid(pid, (0 if blocking else os.WNOHANG)) | |
|
105 | break | |||
105 | except OSError as e: |
|
106 | except OSError as e: | |
106 | if e.errno == errno.EINTR: |
|
107 | if e.errno == errno.EINTR: | |
107 | continue |
|
108 | continue | |
108 | elif e.errno == errno.ECHILD: |
|
109 | elif e.errno == errno.ECHILD: | |
109 | break # ignore ECHILD |
|
110 | break # ignore ECHILD | |
110 | else: |
|
111 | else: | |
111 | raise |
|
112 | raise | |
112 | if p: |
|
113 | if p: | |
113 | pids.remove(p) |
|
114 | pids.remove(p) | |
114 | st = _exitstatus(st) |
|
115 | st = _exitstatus(st) | |
115 | if st and not problem[0]: |
|
116 | if st and not problem[0]: | |
116 | problem[0] = st |
|
117 | problem[0] = st | |
117 | # unregister SIGCHLD handler as all children will be killed |
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118 | # unregister SIGCHLD handler as all children will be killed | |
118 | signal.signal(signal.SIGCHLD, oldchldhandler) |
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119 | signal.signal(signal.SIGCHLD, oldchldhandler) | |
119 | killworkers() |
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120 | killworkers() | |
120 | def sigchldhandler(signum, frame): |
|
121 | def sigchldhandler(signum, frame): | |
121 | waitforworkers(blocking=False) |
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122 | waitforworkers(blocking=False) | |
122 | oldchldhandler = signal.signal(signal.SIGCHLD, sigchldhandler) |
|
123 | oldchldhandler = signal.signal(signal.SIGCHLD, sigchldhandler) | |
123 | for pargs in partition(args, workers): |
|
124 | for pargs in partition(args, workers): | |
124 | pid = os.fork() |
|
125 | pid = os.fork() | |
125 | if pid == 0: |
|
126 | if pid == 0: | |
126 | signal.signal(signal.SIGINT, oldhandler) |
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127 | signal.signal(signal.SIGINT, oldhandler) | |
127 | signal.signal(signal.SIGCHLD, oldchldhandler) |
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128 | signal.signal(signal.SIGCHLD, oldchldhandler) | |
128 | try: |
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129 | try: | |
129 | os.close(rfd) |
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130 | os.close(rfd) | |
130 | for i, item in func(*(staticargs + (pargs,))): |
|
131 | for i, item in func(*(staticargs + (pargs,))): | |
131 | os.write(wfd, '%d %s\n' % (i, item)) |
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132 | os.write(wfd, '%d %s\n' % (i, item)) | |
132 | os._exit(0) |
|
133 | os._exit(0) | |
133 | except KeyboardInterrupt: |
|
134 | except KeyboardInterrupt: | |
134 | os._exit(255) |
|
135 | os._exit(255) | |
135 | # other exceptions are allowed to propagate, we rely |
|
136 | # other exceptions are allowed to propagate, we rely | |
136 | # on lock.py's pid checks to avoid release callbacks |
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137 | # on lock.py's pid checks to avoid release callbacks | |
137 | pids.add(pid) |
|
138 | pids.add(pid) | |
138 | os.close(wfd) |
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139 | os.close(wfd) | |
139 | fp = os.fdopen(rfd, 'rb', 0) |
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140 | fp = os.fdopen(rfd, 'rb', 0) | |
140 | def cleanup(): |
|
141 | def cleanup(): | |
141 | signal.signal(signal.SIGINT, oldhandler) |
|
142 | signal.signal(signal.SIGINT, oldhandler) | |
142 | waitforworkers() |
|
143 | waitforworkers() | |
143 | signal.signal(signal.SIGCHLD, oldchldhandler) |
|
144 | signal.signal(signal.SIGCHLD, oldchldhandler) | |
144 | status = problem[0] |
|
145 | status = problem[0] | |
145 | if status: |
|
146 | if status: | |
146 | if status < 0: |
|
147 | if status < 0: | |
147 | os.kill(os.getpid(), -status) |
|
148 | os.kill(os.getpid(), -status) | |
148 | sys.exit(status) |
|
149 | sys.exit(status) | |
149 | try: |
|
150 | try: | |
150 | for line in util.iterfile(fp): |
|
151 | for line in util.iterfile(fp): | |
151 | l = line.split(' ', 1) |
|
152 | l = line.split(' ', 1) | |
152 | yield int(l[0]), l[1][:-1] |
|
153 | yield int(l[0]), l[1][:-1] | |
153 | except: # re-raises |
|
154 | except: # re-raises | |
154 | killworkers() |
|
155 | killworkers() | |
155 | cleanup() |
|
156 | cleanup() | |
156 | raise |
|
157 | raise | |
157 | cleanup() |
|
158 | cleanup() | |
158 |
|
159 | |||
159 | def _posixexitstatus(code): |
|
160 | def _posixexitstatus(code): | |
160 | '''convert a posix exit status into the same form returned by |
|
161 | '''convert a posix exit status into the same form returned by | |
161 | os.spawnv |
|
162 | os.spawnv | |
162 |
|
163 | |||
163 | returns None if the process was stopped instead of exiting''' |
|
164 | returns None if the process was stopped instead of exiting''' | |
164 | if os.WIFEXITED(code): |
|
165 | if os.WIFEXITED(code): | |
165 | return os.WEXITSTATUS(code) |
|
166 | return os.WEXITSTATUS(code) | |
166 | elif os.WIFSIGNALED(code): |
|
167 | elif os.WIFSIGNALED(code): | |
167 | return -os.WTERMSIG(code) |
|
168 | return -os.WTERMSIG(code) | |
168 |
|
169 | |||
169 | if os.name != 'nt': |
|
170 | if os.name != 'nt': | |
170 | _platformworker = _posixworker |
|
171 | _platformworker = _posixworker | |
171 | _exitstatus = _posixexitstatus |
|
172 | _exitstatus = _posixexitstatus | |
172 |
|
173 | |||
173 | def partition(lst, nslices): |
|
174 | def partition(lst, nslices): | |
174 | '''partition a list into N slices of roughly equal size |
|
175 | '''partition a list into N slices of roughly equal size | |
175 |
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176 | |||
176 | The current strategy takes every Nth element from the input. If |
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177 | The current strategy takes every Nth element from the input. If | |
177 | we ever write workers that need to preserve grouping in input |
|
178 | we ever write workers that need to preserve grouping in input | |
178 | we should consider allowing callers to specify a partition strategy. |
|
179 | we should consider allowing callers to specify a partition strategy. | |
179 |
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180 | |||
180 | mpm is not a fan of this partitioning strategy when files are involved. |
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181 | mpm is not a fan of this partitioning strategy when files are involved. | |
181 | In his words: |
|
182 | In his words: | |
182 |
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183 | |||
183 | Single-threaded Mercurial makes a point of creating and visiting |
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184 | Single-threaded Mercurial makes a point of creating and visiting | |
184 | files in a fixed order (alphabetical). When creating files in order, |
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185 | files in a fixed order (alphabetical). When creating files in order, | |
185 | a typical filesystem is likely to allocate them on nearby regions on |
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186 | a typical filesystem is likely to allocate them on nearby regions on | |
186 | disk. Thus, when revisiting in the same order, locality is maximized |
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187 | disk. Thus, when revisiting in the same order, locality is maximized | |
187 | and various forms of OS and disk-level caching and read-ahead get a |
|
188 | and various forms of OS and disk-level caching and read-ahead get a | |
188 | chance to work. |
|
189 | chance to work. | |
189 |
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190 | |||
190 | This effect can be quite significant on spinning disks. I discovered it |
|
191 | This effect can be quite significant on spinning disks. I discovered it | |
191 | circa Mercurial v0.4 when revlogs were named by hashes of filenames. |
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192 | circa Mercurial v0.4 when revlogs were named by hashes of filenames. | |
192 | Tarring a repo and copying it to another disk effectively randomized |
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193 | Tarring a repo and copying it to another disk effectively randomized | |
193 | the revlog ordering on disk by sorting the revlogs by hash and suddenly |
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194 | the revlog ordering on disk by sorting the revlogs by hash and suddenly | |
194 | performance of my kernel checkout benchmark dropped by ~10x because the |
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195 | performance of my kernel checkout benchmark dropped by ~10x because the | |
195 | "working set" of sectors visited no longer fit in the drive's cache and |
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196 | "working set" of sectors visited no longer fit in the drive's cache and | |
196 | the workload switched from streaming to random I/O. |
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197 | the workload switched from streaming to random I/O. | |
197 |
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198 | |||
198 | What we should really be doing is have workers read filenames from a |
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199 | What we should really be doing is have workers read filenames from a | |
199 | ordered queue. This preserves locality and also keeps any worker from |
|
200 | ordered queue. This preserves locality and also keeps any worker from | |
200 | getting more than one file out of balance. |
|
201 | getting more than one file out of balance. | |
201 | ''' |
|
202 | ''' | |
202 | for i in range(nslices): |
|
203 | for i in range(nslices): | |
203 | yield lst[i::nslices] |
|
204 | yield lst[i::nslices] |
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