##// END OF EJS Templates
discovery: slowly increase sampling size...
discovery: slowly increase sampling size Some pathological discovery runs can requires many roundtrip. When this happens things can get very slow. To make the algorithm more resilience again such pathological case. We slowly increase the sample size with each roundtrip (+5%). This will have a negligible impact on "normal" discovery with few roundtrips, but a large positive impact of case with many roundtrips. Asking more question per roundtrip helps to reduce the undecided set faster. Instead of reducing the undecided set a linear speed (in the worst case), we reduce it as a guaranteed (small) exponential rate. The data below show this slow ramp up in sample size: round trip | 1 | 5 | 10 | 20 | 50 | 100 | 130 | sample size | 200 | 254 | 321 | 517 | 2 199 | 25 123 | 108 549 | covered nodes | 200 | 1 357 | 2 821 | 7 031 | 42 658 | 524 530 | 2 276 755 | To be a bit more concrete, lets take a very pathological case as an example. We are doing discovery from a copy of Mozilla-try to a more recent version of mozilla-unified. Mozilla-unified heads are unknown to the mozilla-try repo and there are over 1 million "missing" changesets. (the discovery is "local" to avoid network interference) Without this change, the discovery: - last 1858 seconds (31 minutes), - does 1700 round trip, - asking about 340 000 nodes. With this change, the discovery: - last 218 seconds (3 minutes, 38 seconds a -88% improvement), - does 94 round trip (-94%), - asking about 344 211 nodes (+1%). Of course, this is an extreme case (and 3 minutes is still slow). However this give a good example of how this sample size increase act as a safety net catching any bad situations. We could image a steeper increase than 5%. For example 10% would give the following number: round trip | 1 | 5 | 10 | 20 | 50 | 75 | 100 | sample size | 200 | 321 | 514 | 1 326 | 23 060 | 249 812 | 2 706 594 | covered nodes | 200 | 1 541 | 3 690 | 12 671 | 251 871 | 2 746 254 | 29 770 966 | In parallel, it is useful to understand these pathological cases and improve them. However the current change provides a general purpose safety net to smooth the impact of pathological cases. To avoid issue with older http server, the increase in sample size only occurs if the protocol has not limit on command argument size.

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util.h
74 lines | 2.0 KiB | text/x-c | CLexer
Yuya Nishihara
cext: move util.h to cext tree...
r32384 /*
util.h - utility functions for interfacing with the various python APIs.
This software may be used and distributed according to the terms of
the GNU General Public License, incorporated herein by reference.
*/
#ifndef _HG_UTIL_H_
#define _HG_UTIL_H_
#include "compat.h"
#if PY_MAJOR_VERSION >= 3
#define IS_PY3K
#endif
Yuya Nishihara
py3: add PY23() macro to switch string literal depending on python version...
r36636 /* helper to switch things like string literal depending on Python version */
#ifdef IS_PY3K
#define PY23(py2, py3) py3
#else
#define PY23(py2, py3) py2
#endif
Augie Fackler
util: add clang-format control comment around struct and format macro...
r34636 /* clang-format off */
Yuya Nishihara
cext: move util.h to cext tree...
r32384 typedef struct {
PyObject_HEAD
char state;
int mode;
int size;
int mtime;
} dirstateTupleObject;
Augie Fackler
util: add clang-format control comment around struct and format macro...
r34636 /* clang-format on */
Yuya Nishihara
cext: move util.h to cext tree...
r32384
extern PyTypeObject dirstateTupleType;
#define dirstate_tuple_check(op) (Py_TYPE(op) == &dirstateTupleType)
André Sintzoff
cext: define MIN macro only if it is not yet defined...
r35793 #ifndef MIN
Augie Fackler
util: add clang-format control comment around struct and format macro...
r34636 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
André Sintzoff
cext: define MIN macro only if it is not yet defined...
r35793 #endif
Yuya Nishihara
cext: move util.h to cext tree...
r32384 /* VC9 doesn't include bool and lacks stdbool.h based on my searching */
#if defined(_MSC_VER) || __STDC_VERSION__ < 199901L
#define true 1
#define false 0
typedef unsigned char bool;
#else
#include <stdbool.h>
#endif
Yuya Nishihara
cext: move _dict_new_presized() to header...
r33751 static inline PyObject *_dict_new_presized(Py_ssize_t expected_size)
{
/* _PyDict_NewPresized expects a minused parameter, but it actually
creates a dictionary that's the nearest power of two bigger than the
parameter. For example, with the initial minused = 1000, the
dictionary created has size 1024. Of course in a lot of cases that
can be greater than the maximum load factor Python's dict object
expects (= 2/3), so as soon as we cross the threshold we'll resize
anyway. So create a dictionary that's at least 3/2 the size. */
return _PyDict_NewPresized(((1 + expected_size) / 2) * 3);
}
Augie Fackler
revlog: replace PyInt_AS_LONG with a more portable helper function...
r40634 /* Convert a PyInt or PyLong to a long. Returns false if there is an
error, in which case an exception will already have been set. */
static inline bool pylong_to_long(PyObject *pylong, long *out)
{
*out = PyLong_AsLong(pylong);
/* Fast path to avoid hitting PyErr_Occurred if the value was obviously
* not an error. */
if (*out != -1) {
return true;
}
return PyErr_Occurred() == NULL;
}
Yuya Nishihara
cext: move util.h to cext tree...
r32384 #endif /* _HG_UTIL_H_ */