worker: change partition strategy to every Nth element
The only consumer of the worker pool code today is `hg update`.
Previously, the algorithm to partition work to each worker process
preserved input list ordering. We'd take the first N elements, then
the next N elements, etc. Measurements on mozilla-central demonstrate
this isn't an optimal partitioning strategy.
I added debug code to print when workers were exiting. When performing
a working copy update on a previously empty working copy of
mozilla-central, I noticed that process lifetimes were all over the
map. One worker would complete after 7s. Many would complete after
12s. And another worker would often take >16s. This behavior occurred
for many worker process counts and was more pronounced on some than
others.
What I suspect is happening is some workers end up with lots of
small files and others with large files. This is because the update
code passes in actions according to sorted filenames. And, directories
under tend to accumulate similar files. For example, test directories
often consist of many small test files and media directories contain
binary (often larger) media files.
This patch changes the partitioning algorithm to select every Nth
element from the input list. Each worker thus has a similar composition
of files to operate on.
The result of this change is that worker processes now all tend to exit
around the same time. The possibility of a long pole due to being
unlucky and receiving all the large files has been mitigated. Overall
execution time seems to drop, but not by a statistically significant
amount on mozilla-central. However, repositories with directories
containing many large files will likely show a drop.
There shouldn't be any regressions due to partial manifest decoding
because the update code already iterates the manifest to determine
what files to operate on, so the manifest should already be decoded.
/*
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_
#if PY_MAJOR_VERSION >= 3
#define IS_PY3K
#define PyInt_FromLong PyLong_FromLong
#define PyInt_AsLong PyLong_AsLong
/*
Mapping of some of the python < 2.x PyString* functions to py3k's PyUnicode.
The commented names below represent those that are present in the PyBytes
definitions for python < 2.6 (below in this file) that don't have a direct
implementation.
*/
#define PyStringObject PyUnicodeObject
#define PyString_Type PyUnicode_Type
#define PyString_Check PyUnicode_Check
#define PyString_CheckExact PyUnicode_CheckExact
#define PyString_CHECK_INTERNED PyUnicode_CHECK_INTERNED
#define PyString_AS_STRING PyUnicode_AsLatin1String
#define PyString_GET_SIZE PyUnicode_GET_SIZE
#define PyString_FromStringAndSize PyUnicode_FromStringAndSize
#define PyString_FromString PyUnicode_FromString
#define PyString_FromFormatV PyUnicode_FromFormatV
#define PyString_FromFormat PyUnicode_FromFormat
/* #define PyString_Size PyUnicode_GET_SIZE */
/* #define PyString_AsString */
/* #define PyString_Repr */
#define PyString_Concat PyUnicode_Concat
#define PyString_ConcatAndDel PyUnicode_AppendAndDel
#define _PyString_Resize PyUnicode_Resize
/* #define _PyString_Eq */
#define PyString_Format PyUnicode_Format
/* #define _PyString_FormatLong */
/* #define PyString_DecodeEscape */
#define _PyString_Join PyUnicode_Join
#define PyString_Decode PyUnicode_Decode
#define PyString_Encode PyUnicode_Encode
#define PyString_AsEncodedObject PyUnicode_AsEncodedObject
#define PyString_AsEncodedString PyUnicode_AsEncodedString
#define PyString_AsDecodedObject PyUnicode_AsDecodedObject
#define PyString_AsDecodedString PyUnicode_AsDecodedUnicode
/* #define PyString_AsStringAndSize */
#define _PyString_InsertThousandsGrouping _PyUnicode_InsertThousandsGrouping
#endif /* PY_MAJOR_VERSION */
#ifdef _WIN32
#ifdef _MSC_VER
/* msvc 6.0 has problems */
#define inline __inline
typedef signed char int8_t;
typedef short int16_t;
typedef long int32_t;
typedef __int64 int64_t;
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned long uint32_t;
typedef unsigned __int64 uint64_t;
#else
#include <stdint.h>
#endif
#else
/* not windows */
#include <sys/types.h>
#if defined __BEOS__ && !defined __HAIKU__
#include <ByteOrder.h>
#else
#include <arpa/inet.h>
#endif
#include <inttypes.h>
#endif
#if defined __hpux || defined __SUNPRO_C || defined _AIX
#define inline
#endif
#ifdef __linux
#define inline __inline
#endif
typedef struct {
PyObject_HEAD
char state;
int mode;
int size;
int mtime;
} dirstateTupleObject;
extern PyTypeObject dirstateTupleType;
#define dirstate_tuple_check(op) (Py_TYPE(op) == &dirstateTupleType)
static inline uint32_t getbe32(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
return ((d[0] << 24) |
(d[1] << 16) |
(d[2] << 8) |
(d[3]));
}
static inline int16_t getbeint16(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
return ((d[0] << 8) |
(d[1]));
}
static inline uint16_t getbeuint16(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
return ((d[0] << 8) |
(d[1]));
}
static inline void putbe32(uint32_t x, char *c)
{
c[0] = (x >> 24) & 0xff;
c[1] = (x >> 16) & 0xff;
c[2] = (x >> 8) & 0xff;
c[3] = (x) & 0xff;
}
static inline double getbefloat64(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
double ret;
int i;
uint64_t t = 0;
for (i = 0; i < 8; i++) {
t = (t<<8) + d[i];
}
memcpy(&ret, &t, sizeof(t));
return ret;
}
/* This should be kept in sync with normcasespecs in encoding.py. */
enum normcase_spec {
NORMCASE_LOWER = -1,
NORMCASE_UPPER = 1,
NORMCASE_OTHER = 0
};
#define MIN(a, b) (((a)<(b))?(a):(b))
/* 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
#endif /* _HG_UTIL_H_ */