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> I can see a couple possible downsides: (a) the library might have some
> weird behavior across fork boundaries; (b) the additional memory space > that has to be duplicated into child processes will cost something per > child launch, even if the child never uses it. But these are only > arguments that it might not *always* be a prudent thing to do, not that > we shouldn't give the DBA the tool to do it if he wants. So fire away. Here is a patch for the above, including a documentation update. It creates a new GUC variable "preload_libraries", that accepts a list in the form: preload_libraries = '$libdir/mylib1:initfunc,$libdir/mylib2' If ":initfunc" is omitted or not found, no initialization function is executed, but the library is still preloaded. If "$libdir/mylib" isn't found, the postmaster refuses to start. In my testing with PL/R, it reduces the first call to a PL/R function (after connecting) from almost 2 seconds, down to about 8 ms. Joe Conway
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6 files changed

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lines changed

‎doc/src/sgml/runtime.sgml

Lines changed: 30 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.171 2003/03/20 03:34:55 momjian Exp $
2+
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.172 2003/03/20 04:51:44 momjian Exp $
33
-->
44

55
<Chapter Id="runtime">
@@ -1799,6 +1799,35 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
17991799
</listitem>
18001800
</varlistentry>
18011801

1802+
<varlistentry>
1803+
<term><varname>PRELOAD_LIBRARIES</varname> (<type>string</type>)</term>
1804+
<indexterm><primary>preload_libraries</></>
1805+
<listitem>
1806+
<para>
1807+
This variable specifies one or more shared libraries that are to be
1808+
preloaded at Postmaster start. An initialization function can also be
1809+
optionally specified by adding a colon followed by the name of the
1810+
initialization function after the library name. For example
1811+
<literal>'$libdir/mylib:init_mylib'</literal> would cause <literal>mylib</>
1812+
to be preloaded and <literal>init_mylib</> to be executed. If more than
1813+
one library is to be loaded, they must be delimited with a comma.
1814+
</para>
1815+
1816+
<para>
1817+
If <literal>mylib</> is not found, the postmaster will fail to start.
1818+
However, if <literal>init_mylib</> is not found, <literal>mylib</> will
1819+
still be preloaded without executing the initialization function.
1820+
</para>
1821+
1822+
<para>
1823+
By preloading a shared library (and initializing it if applicable),
1824+
the library startup time is avoided when the library is used later in a
1825+
specific backend. However there is a cost in terms of memory duplication
1826+
as every backend is forked, whether or not the library is used.
1827+
</para>
1828+
</listitem>
1829+
</varlistentry>
1830+
18021831
<varlistentry>
18031832
<term><varname>REGEX_FLAVOR</varname> (<type>string</type>)</term>
18041833
<indexterm><primary>regular expressions</></>

‎src/backend/postmaster/postmaster.c

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,7 @@
3737
*
3838
*
3939
* IDENTIFICATION
40-
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.307 2003/02/23 04:48:19 tgl Exp $
40+
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.308 2003/03/20 04:51:44 momjian Exp $
4141
*
4242
* NOTES
4343
*
@@ -205,6 +205,8 @@ bool LogSourcePort;
205205
bool Log_connections = false;
206206
bool Db_user_namespace = false;
207207

208+
/* list of library:init-function to be preloaded */
209+
char *preload_libraries_string = NULL;
208210

209211
/* Startup/shutdown state */
210212
static pid_t StartupPID = 0,
@@ -645,6 +647,13 @@ PostmasterMain(int argc, char *argv[])
645647
secure_initialize();
646648
#endif
647649

650+
/*
651+
* process any libraries that should be preloaded and
652+
* optionally pre-initialized
653+
*/
654+
if (preload_libraries_string)
655+
process_preload_libraries(preload_libraries_string);
656+
648657
/*
649658
* Fork away from controlling terminal, if -S specified.
650659
*

‎src/backend/utils/init/miscinit.c

Lines changed: 90 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.100 2003/01/27 00:51:06 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.101 2003/03/20 04:51:44 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1044,3 +1044,92 @@ ValidatePgVersion(const char *path)
10441044
"which is not compatible with this version %s.",
10451045
file_major, file_minor, version_string);
10461046
}
1047+
1048+
/*-------------------------------------------------------------------------
1049+
* Library preload support
1050+
*-------------------------------------------------------------------------
1051+
*/
1052+
1053+
#if defined(__mc68000__) && defined(__ELF__)
1054+
typedef int32 ((*func_ptr) ());
1055+
#else
1056+
typedef char *((*func_ptr) ());
1057+
#endif
1058+
1059+
/*
1060+
* process any libraries that should be preloaded and
1061+
* optionally pre-initialized
1062+
*/
1063+
void
1064+
process_preload_libraries(char *preload_libraries_string)
1065+
{
1066+
char *rawstring;
1067+
List *elemlist;
1068+
List *l;
1069+
1070+
if (preload_libraries_string == NULL)
1071+
return;
1072+
1073+
/* Need a modifiable copy of string */
1074+
rawstring = pstrdup(preload_libraries_string);
1075+
1076+
/* Parse string into list of identifiers */
1077+
if (!SplitIdentifierString(rawstring, ',', &elemlist))
1078+
{
1079+
/* syntax error in list */
1080+
pfree(rawstring);
1081+
freeList(elemlist);
1082+
elog(LOG, "invalid list syntax for preload_libraries configuration option");
1083+
}
1084+
1085+
foreach(l, elemlist)
1086+
{
1087+
char *tok = (char *) lfirst(l);
1088+
char *sep = strstr(tok, ":");
1089+
char *filename = NULL;
1090+
char *funcname = NULL;
1091+
func_ptr initfunc;
1092+
1093+
if (sep)
1094+
{
1095+
/*
1096+
* a colon separator implies there is an initialization function
1097+
* that we need to run in addition to loading the library
1098+
*/
1099+
size_t filename_len = sep - tok;
1100+
size_t funcname_len = strlen(tok) - filename_len - 1;
1101+
1102+
filename = (char *) palloc(filename_len + 1);
1103+
memset(filename, '\0', filename_len + 1);
1104+
snprintf(filename, filename_len + 1, "%s", tok);
1105+
1106+
funcname = (char *) palloc(funcname_len + 1);
1107+
memset(funcname, '\0', funcname_len + 1);
1108+
snprintf(funcname, funcname_len + 1, "%s", sep + 1);
1109+
}
1110+
else
1111+
{
1112+
/*
1113+
* no separator -- just load the library
1114+
*/
1115+
filename = pstrdup(tok);
1116+
funcname = NULL;
1117+
}
1118+
1119+
initfunc = (func_ptr) load_external_function(filename, funcname, false, NULL);
1120+
if (initfunc)
1121+
(*initfunc)();
1122+
1123+
elog(LOG, "preloaded library %s with initialization function %s", filename, funcname);
1124+
1125+
if (filename != NULL)
1126+
pfree(filename);
1127+
1128+
if (funcname != NULL)
1129+
pfree(funcname);
1130+
}
1131+
1132+
pfree(rawstring);
1133+
freeList(elemlist);
1134+
}
1135+

‎src/backend/utils/misc/guc.c

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@
55
* command, configuration file, and command line options.
66
* See src/backend/utils/misc/README for more information.
77
*
8-
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.116 2003/03/04 21:51:21 tgl Exp $
8+
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.117 2003/03/20 04:51:44 momjian Exp $
99
*
1010
* Copyright 2000 by PostgreSQL Global Development Group
1111
* Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -60,6 +60,7 @@ extern int CheckPointTimeout;
6060
extern bool autocommit;
6161
extern int CommitDelay;
6262
extern int CommitSiblings;
63+
extern char *preload_libraries_string;
6364

6465
#ifdef HAVE_SYSLOG
6566
extern char *Syslog_facility;
@@ -814,6 +815,12 @@ static struct config_string
814815
"C", locale_time_assign, NULL
815816
},
816817

818+
{
819+
{"preload_libraries", PGC_POSTMASTER, GUC_LIST_INPUT | GUC_LIST_QUOTE},
820+
&preload_libraries_string,
821+
"", NULL, NULL
822+
},
823+
817824
{
818825
{"regex_flavor", PGC_USERSET}, &regex_flavor_string,
819826
"advanced", assign_regex_flavor, NULL

‎src/backend/utils/misc/postgresql.conf.sample

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -214,4 +214,5 @@
214214
#transform_null_equals = false
215215
#statement_timeout = 0 # 0 is disabled, in milliseconds
216216
#db_user_namespace = false
217+
#preload_libraries = ''
217218

‎src/include/miscadmin.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
1313
* Portions Copyright (c) 1994, Regents of the University of California
1414
*
15-
* $Id: miscadmin.h,v 1.116 2003/02/22 05:57:45 tgl Exp $
15+
* $Id: miscadmin.h,v 1.117 2003/03/20 04:51:44 momjian Exp $
1616
*
1717
* NOTES
1818
* some of the information in this file should be moved to
@@ -288,6 +288,7 @@ extern void RecordSharedMemoryInLockFile(unsigned long id1,
288288
unsigned long id2);
289289

290290
extern void ValidatePgVersion(const char *path);
291+
extern void process_preload_libraries(char *preload_libraries_string);
291292

292293
/* these externs do not belong here... */
293294
extern void IgnoreSystemIndexes(bool mode);

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