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> I can see a couple possible downsides: (a) the library might have some

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> 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
This commit is contained in:
Bruce Momjian
2003-03-20 04:51:44 +00:00
parent e733510d5d
commit 15ce2d2e4a
6 changed files with 141 additions and 5 deletions
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91
src/backend/utils/init/miscinit.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.100 2003/01/27 00:51:06 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.101 2003/03/20 04:51:44 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -1044,3 +1044,92 @@ ValidatePgVersion(const char *path)
"which is not compatible with this version %s.",
file_major, file_minor, version_string);
}
/*-------------------------------------------------------------------------
* Library preload support
*-------------------------------------------------------------------------
*/
#if defined(__mc68000__) && defined(__ELF__)
typedef int32 ((*func_ptr) ());
#else
typedef char *((*func_ptr) ());
#endif
/*
* process any libraries that should be preloaded and
* optionally pre-initialized
*/
void
process_preload_libraries(char *preload_libraries_string)
{
char *rawstring;
List *elemlist;
List *l;
if (preload_libraries_string == NULL)
return;
/* Need a modifiable copy of string */
rawstring = pstrdup(preload_libraries_string);
/* Parse string into list of identifiers */
if (!SplitIdentifierString(rawstring, ',', &elemlist))
{
/* syntax error in list */
pfree(rawstring);
freeList(elemlist);
elog(LOG, "invalid list syntax for preload_libraries configuration option");
}
foreach(l, elemlist)
{
char *tok = (char *) lfirst(l);
char *sep = strstr(tok, ":");
char *filename = NULL;
char *funcname = NULL;
func_ptr initfunc;
if (sep)
{
/*
* a colon separator implies there is an initialization function
* that we need to run in addition to loading the library
*/
size_t filename_len = sep - tok;
size_t funcname_len = strlen(tok) - filename_len - 1;
filename = (char *) palloc(filename_len + 1);
memset(filename, '\0', filename_len + 1);
snprintf(filename, filename_len + 1, "%s", tok);
funcname = (char *) palloc(funcname_len + 1);
memset(funcname, '\0', funcname_len + 1);
snprintf(funcname, funcname_len + 1, "%s", sep + 1);
}
else
{
/*
* no separator -- just load the library
*/
filename = pstrdup(tok);
funcname = NULL;
}
initfunc = (func_ptr) load_external_function(filename, funcname, false, NULL);
if (initfunc)
(*initfunc)();
elog(LOG, "preloaded library %s with initialization function %s", filename, funcname);
if (filename != NULL)
pfree(filename);
if (funcname != NULL)
pfree(funcname);
}
pfree(rawstring);
freeList(elemlist);
}