Re: [HACKERS] loading libraries on Postmaster startup

Newest patch applied. Thanks.

---------------------------------------------------------------------------

Joe Conway wrote:
> Joe Conway wrote:
> > Tom Lane wrote:
> >> Joe Conway <mail(at)joeconway(dot)com> writes:
> >>> 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.
> >>
> >> Hm, pretty significant. Can you measure any per-fork cost (ie, the loss
> >> incurred by children that don't use PL/R)? Is there any measurable
> >> benefit for our other PLs (plperl etc)?
> >
> > Here's what I got:
> >
> > 10000 connect/disconnect in tight loop
> > ----------------------------------------------------------
> > condition time top
> > ----------------------------------------------------------
> > with no preload 87 seconds ~10% CPU, ~2.2 MB
> > with plr preload 133 seconds ~10% CPU, ~13 MB
> > with plperl preload 92 seconds ~10% CPU, ~3.2 MB
> > with pltcl preload 88 seconds ~10% CPU, ~2.3 MB
> > with plpython preload 93 seconds ~10% CPU, ~2.3 MB
> >
> >
> > 1000 connect/"select some_simple_func()"/disconnect in tight loop
> > ------------------------------------------------------------------
> > condition time top
> > ------------------------------------------------------------------
> > plr-func without preload 739 seconds ~60% CPU, ~13 MB
> > plr-func with preload 26 seconds ~10% CPU, ~13 MB
> > plperl-func without preload 46 seconds ~4% CPU, ~3.2 MB
> > plperl-func with preload 33 seconds ~3% CPU, ~3.2 MB
> > pltcl-func without preload 22 seconds ~5% CPU, ~2.3 MB
> > pltcl-func with preload 17 seconds ~4% CPU, ~2.3 MB
> > plpython-func without preload 33 seconds ~4% CPU, ~2.3 MB
> > plpython-func with preload 31 seconds ~4% CPU, ~2.3 MB
> >
>
> Here's an updated copy of the patch. The original patch was failing due
> to code drift in cvs.
>
> Peter's suggestion (__attribute__((constructor))) is interesting, but it
> appears to be a gcc specific extension, and hence non-portable.
>
> I'd still like to see this applied if there are no other objections.
> From the above info it is apparent that the benefit outweighs the cost
> for plperl and pltcl (although not as significantly as for plr).
>
> Joe

> Index: doc/src/sgml/runtime.sgml
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/doc/src/sgml/runtime.sgml,v
> retrieving revision 1.169
> diff -c -r1.169 runtime.sgml
> *** doc/src/sgml/runtime.sgml 19 Feb 2003 04:06:28 -0000 1.169
> --- doc/src/sgml/runtime.sgml 27 Feb 2003 18:46:39 -0000
> ***************
> *** 1781,1786 ****
> --- 1781,1815 ----
> </varlistentry>
>
> <varlistentry>
> + <term><varname>PRELOAD_LIBRARIES</varname> (<type>string</type>)</term>
> + <indexterm><primary>preload_libraries</></>
> + <listitem>
> + <para>
> + This variable specifies one or more shared libraries that are to be
> + preloaded at Postmaster start. An initialization function can also be
> + optionally specified by adding a colon followed by the name of the
> + initialization function after the library name. For example
> + <literal>'$libdir/mylib:init_mylib'</literal> would cause <literal>mylib</>
> + to be preloaded and <literal>init_mylib</> to be executed. If more than
> + one library is to be loaded, they must be delimited with a comma.
> + </para>
> +
> + <para>
> + If <literal>mylib</> is not found, the postmaster will fail to start.
> + However, if <literal>init_mylib</> is not found, <literal>mylib</> will
> + still be preloaded without executing the initialization function.
> + </para>
> +
> + <para>
> + By preloading a shared library (and initializing it if applicable),
> + the library startup time is avoided when the library is used later in a
> + specific backend. However there is a cost in terms of memory duplication
> + as every backend is forked, whether or not the library is used.
> + </para>
> + </listitem>
> + </varlistentry>
> +
> + <varlistentry>
> <term><varname>REGEX_FLAVOR</varname> (<type>string</type>)</term>
> <indexterm><primary>regular expressions</></>
> <listitem>
> Index: src/backend/postmaster/postmaster.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/src/backend/postmaster/postmaster.c,v
> retrieving revision 1.307
> diff -c -r1.307 postmaster.c
> *** src/backend/postmaster/postmaster.c 23 Feb 2003 04:48:19 -0000 1.307
> --- src/backend/postmaster/postmaster.c 27 Feb 2003 18:46:39 -0000
> ***************
> *** 205,210 ****
> --- 205,212 ----
> bool Log_connections = false;
> bool Db_user_namespace = false;
>
> + /* list of library:init-function to be preloaded */
> + char *preload_libraries_string = NULL;
>
> /* Startup/shutdown state */
> static pid_t StartupPID = 0,
> ***************
> *** 644,649 ****
> --- 646,658 ----
> if (EnableSSL)
> secure_initialize();
> #endif
> +
> + /*
> + * process any libraries that should be preloaded and
> + * optionally pre-initialized
> + */
> + if (preload_libraries_string)
> + process_preload_libraries(preload_libraries_string);
>
> /*
> * Fork away from controlling terminal, if -S specified.
> Index: src/backend/utils/init/miscinit.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/src/backend/utils/init/miscinit.c,v
> retrieving revision 1.100
> diff -c -r1.100 miscinit.c
> *** src/backend/utils/init/miscinit.c 27 Jan 2003 00:51:06 -0000 1.100
> --- src/backend/utils/init/miscinit.c 27 Feb 2003 18:46:39 -0000
> ***************
> *** 1044,1046 ****
> --- 1044,1135 ----
> "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);
> + }
> +
> Index: src/backend/utils/misc/guc.c
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/src/backend/utils/misc/guc.c,v
> retrieving revision 1.115
> diff -c -r1.115 guc.c
> *** src/backend/utils/misc/guc.c 23 Feb 2003 23:27:21 -0000 1.115
> --- src/backend/utils/misc/guc.c 27 Feb 2003 18:46:39 -0000
> ***************
> *** 60,65 ****
> --- 60,66 ----
> extern bool autocommit;
> extern int CommitDelay;
> extern int CommitSiblings;
> + extern char *preload_libraries_string;
>
> #ifdef HAVE_SYSLOG
> extern char *Syslog_facility;
> ***************
> *** 812,817 ****
> --- 813,824 ----
> {
> {"lc_time", PGC_USERSET}, &locale_time,
> "C", locale_time_assign, NULL
> + },
> +
> + {
> + {"preload_libraries", PGC_POSTMASTER, GUC_LIST_INPUT | GUC_LIST_QUOTE},
> + &preload_libraries_string,
> + "", NULL, NULL
> },
>
> {
> Index: src/backend/utils/misc/postgresql.conf.sample
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/src/backend/utils/misc/postgresql.conf.sample,v
> retrieving revision 1.70
> diff -c -r1.70 postgresql.conf.sample
> *** src/backend/utils/misc/postgresql.conf.sample 6 Feb 2003 20:25:33 -0000 1.70
> --- src/backend/utils/misc/postgresql.conf.sample 27 Feb 2003 18:46:39 -0000
> ***************
> *** 213,216 ****
> --- 213,217 ----
> #transform_null_equals = false
> #statement_timeout = 0 # 0 is disabled, in milliseconds
> #db_user_namespace = false
> + #preload_libraries = ''
>
> Index: src/include/miscadmin.h
> ===================================================================
> RCS file: /opt/src/cvs/pgsql-server/src/include/miscadmin.h,v
> retrieving revision 1.116
> diff -c -r1.116 miscadmin.h
> *** src/include/miscadmin.h 22 Feb 2003 05:57:45 -0000 1.116
> --- src/include/miscadmin.h 27 Feb 2003 18:46:39 -0000
> ***************
> *** 288,293 ****
> --- 288,294 ----
> unsigned long id2);
>
> extern void ValidatePgVersion(const char *path);
> + extern void process_preload_libraries(char *preload_libraries_string);
>
> /* these externs do not belong here... */
> extern void IgnoreSystemIndexes(bool mode);

>
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