Do a direct probe during postmaster startup to determine the maximum
number of openable files and the number already opened. This eliminates depending on sysconf(_SC_OPEN_MAX), and allows much saner behavior on platforms where open-file slots are used up by semaphores.
This commit is contained in:
Tom Lane
parent
b4c8dcb294
commit
f83356c7f5
|
|
@ -1,5 +1,5 @@
|
|||
<!--
|
||||
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.241 2004/02/17 07:36:47 tgl Exp $
|
||||
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.242 2004/02/23 20:45:58 tgl Exp $
|
||||
-->
|
||||
|
||||
<Chapter Id="runtime">
|
||||
|
|
@ -932,19 +932,14 @@ SET ENABLE_SEQSCAN TO OFF;
|
|||
<listitem>
|
||||
<para>
|
||||
Sets the maximum number of simultaneously open files allowed to each
|
||||
server subprocess. The default is 1000. The limit actually used
|
||||
by the code is the smaller of this setting and the result of
|
||||
<literal>sysconf(_SC_OPEN_MAX)</literal>. Therefore, on systems
|
||||
where <function>sysconf</> returns a reasonable limit, you don't
|
||||
need to worry about this setting. But on some platforms
|
||||
(notably, most BSD systems), <function>sysconf</> returns a
|
||||
value that is much larger than the system can really support
|
||||
when a large number of processes all try to open that many
|
||||
files. If you find yourself seeing <quote>Too many open files</>
|
||||
failures, try reducing this setting. This option can only be set
|
||||
at server start or in the <filename>postgresql.conf</filename>
|
||||
configuration file; if changed in the configuration file, it
|
||||
only affects subsequently-started server subprocesses.
|
||||
server subprocess. The default is 1000. If the kernel is enforcing
|
||||
a safe per-process limit, you don't need to worry about this setting.
|
||||
But on some platforms (notably, most BSD systems), the kernel will
|
||||
allow individual processes to open many more files than the system
|
||||
can really support when a large number of processes all try to open
|
||||
that many files. If you find yourself seeing <quote>Too many open
|
||||
files</> failures, try reducing this setting.
|
||||
This option can only be set at server start.
|
||||
</para>
|
||||
</listitem>
|
||||
</varlistentry>
|
||||
|
|
|
|||
|
|
@ -37,7 +37,7 @@
|
|||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.367 2004/02/17 03:54:56 momjian Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.368 2004/02/23 20:45:59 tgl Exp $
|
||||
*
|
||||
* NOTES
|
||||
*
|
||||
|
|
@ -839,6 +839,12 @@ PostmasterMain(int argc, char *argv[])
|
|||
*/
|
||||
reset_shared(PostPortNumber);
|
||||
|
||||
/*
|
||||
* Estimate number of openable files. This must happen after setting up
|
||||
* semaphores, because on some platforms semaphores count as open files.
|
||||
*/
|
||||
set_max_safe_fds();
|
||||
|
||||
/*
|
||||
* Initialize the list of active backends.
|
||||
*/
|
||||
|
|
@ -848,13 +854,10 @@ PostmasterMain(int argc, char *argv[])
|
|||
/*
|
||||
* Initialize the child pid/HANDLE arrays
|
||||
*/
|
||||
/* FIXME: [fork/exec] Ideally, we would resize these arrays with changes
|
||||
* in MaxBackends, but this'll do as a first order solution.
|
||||
*/
|
||||
win32_childPIDArray = (pid_t*)malloc(NUM_BACKENDARRAY_ELEMS*sizeof(pid_t));
|
||||
win32_childHNDArray = (HANDLE*)malloc(NUM_BACKENDARRAY_ELEMS*sizeof(HANDLE));
|
||||
if (!win32_childPIDArray || !win32_childHNDArray)
|
||||
ereport(LOG,
|
||||
ereport(FATAL,
|
||||
(errcode(ERRCODE_OUT_OF_MEMORY),
|
||||
errmsg("out of memory")));
|
||||
#endif
|
||||
|
|
|
|||
|
|
@ -7,7 +7,7 @@
|
|||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $PostgreSQL: pgsql/src/backend/storage/file/fd.c,v 1.106 2004/01/26 22:35:32 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/storage/file/fd.c,v 1.107 2004/02/23 20:45:59 tgl Exp $
|
||||
*
|
||||
* NOTES:
|
||||
*
|
||||
|
|
@ -54,41 +54,50 @@
|
|||
|
||||
|
||||
/*
|
||||
* Problem: Postgres does a system(ld...) to do dynamic loading.
|
||||
* This will open several extra files in addition to those used by
|
||||
* Postgres. We need to guarantee that there are file descriptors free
|
||||
* for ld to use.
|
||||
* We must leave some file descriptors free for system(), the dynamic loader,
|
||||
* and other code that tries to open files without consulting fd.c. This
|
||||
* is the number left free. (While we can be pretty sure we won't get
|
||||
* EMFILE, there's never any guarantee that we won't get ENFILE due to
|
||||
* other processes chewing up FDs. So it's a bad idea to try to open files
|
||||
* without consulting fd.c. Nonetheless we cannot control all code.)
|
||||
*
|
||||
* The current solution is to limit the number of file descriptors
|
||||
* that this code will allocate at one time: it leaves RESERVE_FOR_LD free.
|
||||
*
|
||||
* (Even though most dynamic loaders now use dlopen(3) or the
|
||||
* equivalent, the OS must still open several files to perform the
|
||||
* dynamic loading. And stdin/stdout/stderr count too. Keep this here.)
|
||||
* Because this is just a fixed setting, we are effectively assuming that
|
||||
* no such code will leave FDs open over the long term; otherwise the slop
|
||||
* is likely to be insufficient. Note in particular that we expect that
|
||||
* loading a shared library does not result in any permanent increase in
|
||||
* the number of open files. (This appears to be true on most if not
|
||||
* all platforms as of Feb 2004.)
|
||||
*/
|
||||
#ifndef RESERVE_FOR_LD
|
||||
#define RESERVE_FOR_LD 10
|
||||
#endif
|
||||
#define NUM_RESERVED_FDS 10
|
||||
|
||||
/*
|
||||
* We need to ensure that we have at least some file descriptors
|
||||
* available to postgreSQL after we've reserved the ones for LD,
|
||||
* so we set that value here.
|
||||
*
|
||||
* I think 10 is an appropriate value so that's what it'll be
|
||||
* for now.
|
||||
* If we have fewer than this many usable FDs after allowing for the reserved
|
||||
* ones, choke.
|
||||
*/
|
||||
#ifndef FD_MINFREE
|
||||
#define FD_MINFREE 10
|
||||
#endif
|
||||
#define FD_MINFREE 10
|
||||
|
||||
|
||||
/*
|
||||
* A number of platforms return values for sysconf(_SC_OPEN_MAX) that are
|
||||
* far beyond what they can really support. This GUC parameter limits what
|
||||
* we will believe.
|
||||
* A number of platforms allow individual processes to open many more files
|
||||
* than they can really support when *many* processes do the same thing.
|
||||
* This GUC parameter lets the DBA limit max_safe_fds to something less than
|
||||
* what the postmaster's initial probe suggests will work.
|
||||
*/
|
||||
int max_files_per_process = 1000;
|
||||
|
||||
/*
|
||||
* Maximum number of file descriptors to open for either VFD entries or
|
||||
* AllocateFile files. This is initialized to a conservative value, and
|
||||
* remains that way indefinitely in bootstrap or standalone-backend cases.
|
||||
* In normal postmaster operation, the postmaster calls set_max_safe_fds()
|
||||
* late in initialization to update the value, and that value is then
|
||||
* inherited by forked subprocesses.
|
||||
*
|
||||
* Note: the value of max_files_per_process is taken into account while
|
||||
* setting this variable, and so need not be tested separately.
|
||||
*/
|
||||
static int max_safe_fds = 32; /* default if not changed */
|
||||
|
||||
|
||||
/* Debugging.... */
|
||||
|
||||
|
|
@ -199,7 +208,6 @@ static void FreeVfd(File file);
|
|||
static int FileAccess(File file);
|
||||
static File fileNameOpenFile(FileName fileName, int fileFlags, int fileMode);
|
||||
static char *filepath(const char *filename);
|
||||
static long pg_nofile(void);
|
||||
static void AtProcExit_Files(int code, Datum arg);
|
||||
static void CleanupTempFiles(bool isProcExit);
|
||||
|
||||
|
|
@ -236,6 +244,105 @@ pg_fdatasync(int fd)
|
|||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* count_usable_fds --- count how many FDs the system will let us open,
|
||||
* and estimate how many are already open.
|
||||
*
|
||||
* We assume stdin (FD 0) is available for dup'ing
|
||||
*/
|
||||
static void
|
||||
count_usable_fds(int *usable_fds, int *already_open)
|
||||
{
|
||||
int *fd;
|
||||
int size;
|
||||
int used = 0;
|
||||
int highestfd = 0;
|
||||
int j;
|
||||
|
||||
size = 1024;
|
||||
fd = (int *) palloc(size * sizeof(int));
|
||||
|
||||
/* dup until failure ... */
|
||||
for (;;)
|
||||
{
|
||||
int thisfd;
|
||||
|
||||
thisfd = dup(0);
|
||||
if (thisfd < 0)
|
||||
{
|
||||
/* Expect EMFILE or ENFILE, else it's fishy */
|
||||
if (errno != EMFILE && errno != ENFILE)
|
||||
elog(WARNING, "dup(0) failed after %d successes: %m", used);
|
||||
break;
|
||||
}
|
||||
|
||||
if (used >= size)
|
||||
{
|
||||
size *= 2;
|
||||
fd = (int *) repalloc(fd, size * sizeof(int));
|
||||
}
|
||||
fd[used++] = thisfd;
|
||||
|
||||
if (highestfd < thisfd)
|
||||
highestfd = thisfd;
|
||||
}
|
||||
|
||||
/* release the files we opened */
|
||||
for (j = 0; j < used; j++)
|
||||
close(fd[j]);
|
||||
|
||||
pfree(fd);
|
||||
|
||||
/*
|
||||
* Return results. usable_fds is just the number of successful dups.
|
||||
* We assume that the system limit is highestfd+1 (remember 0 is a legal
|
||||
* FD number) and so already_open is highestfd+1 - usable_fds.
|
||||
*/
|
||||
*usable_fds = used;
|
||||
*already_open = highestfd+1 - used;
|
||||
}
|
||||
|
||||
/*
|
||||
* set_max_safe_fds
|
||||
* Determine number of filedescriptors that fd.c is allowed to use
|
||||
*/
|
||||
void
|
||||
set_max_safe_fds(void)
|
||||
{
|
||||
int usable_fds;
|
||||
int already_open;
|
||||
|
||||
/*
|
||||
* We want to set max_safe_fds to
|
||||
* MIN(usable_fds, max_files_per_process - already_open)
|
||||
* less the slop factor for files that are opened without consulting
|
||||
* fd.c. This ensures that we won't exceed either max_files_per_process
|
||||
* or the experimentally-determined EMFILE limit.
|
||||
*/
|
||||
count_usable_fds(&usable_fds, &already_open);
|
||||
|
||||
max_safe_fds = Min(usable_fds, max_files_per_process - already_open);
|
||||
|
||||
/*
|
||||
* Take off the FDs reserved for system() etc.
|
||||
*/
|
||||
max_safe_fds -= NUM_RESERVED_FDS;
|
||||
|
||||
/*
|
||||
* Make sure we still have enough to get by.
|
||||
*/
|
||||
if (max_safe_fds < FD_MINFREE)
|
||||
ereport(FATAL,
|
||||
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
|
||||
errmsg("insufficient file descriptors available to start server process"),
|
||||
errdetail("System allows %d, we need at least %d.",
|
||||
max_safe_fds + NUM_RESERVED_FDS,
|
||||
FD_MINFREE + NUM_RESERVED_FDS)));
|
||||
|
||||
elog(DEBUG2, "max_safe_fds = %d, usable_fds = %d, already_open = %d",
|
||||
max_safe_fds, usable_fds, already_open);
|
||||
}
|
||||
|
||||
/*
|
||||
* BasicOpenFile --- same as open(2) except can free other FDs if needed
|
||||
*
|
||||
|
|
@ -279,63 +386,6 @@ tryAgain:
|
|||
return -1; /* failure */
|
||||
}
|
||||
|
||||
/*
|
||||
* pg_nofile: determine number of filedescriptors that fd.c is allowed to use
|
||||
*/
|
||||
static long
|
||||
pg_nofile(void)
|
||||
{
|
||||
static long no_files = 0;
|
||||
|
||||
/* need do this calculation only once */
|
||||
if (no_files == 0)
|
||||
{
|
||||
/*
|
||||
* Ask the system what its files-per-process limit is.
|
||||
*/
|
||||
#ifdef HAVE_SYSCONF
|
||||
no_files = sysconf(_SC_OPEN_MAX);
|
||||
if (no_files <= 0)
|
||||
{
|
||||
#ifdef NOFILE
|
||||
no_files = (long) NOFILE;
|
||||
#else
|
||||
no_files = (long) max_files_per_process;
|
||||
#endif
|
||||
elog(LOG, "sysconf(_SC_OPEN_MAX) failed; using %ld",
|
||||
no_files);
|
||||
}
|
||||
#else /* !HAVE_SYSCONF */
|
||||
#ifdef NOFILE
|
||||
no_files = (long) NOFILE;
|
||||
#else
|
||||
no_files = (long) max_files_per_process;
|
||||
#endif
|
||||
#endif /* HAVE_SYSCONF */
|
||||
|
||||
/*
|
||||
* Some platforms return hopelessly optimistic values. Apply a
|
||||
* configurable upper limit.
|
||||
*/
|
||||
if (no_files > (long) max_files_per_process)
|
||||
no_files = (long) max_files_per_process;
|
||||
|
||||
/*
|
||||
* Make sure we have enough to get by after reserving some for LD.
|
||||
*/
|
||||
if ((no_files - RESERVE_FOR_LD) < FD_MINFREE)
|
||||
ereport(FATAL,
|
||||
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
|
||||
errmsg("insufficient file descriptors available to start server process"),
|
||||
errdetail("System allows %ld, we need at least %d.",
|
||||
no_files, RESERVE_FOR_LD + FD_MINFREE)));
|
||||
|
||||
no_files -= RESERVE_FOR_LD;
|
||||
}
|
||||
|
||||
return no_files;
|
||||
}
|
||||
|
||||
#if defined(FDDEBUG)
|
||||
|
||||
static void
|
||||
|
|
@ -439,7 +489,7 @@ LruInsert(File file)
|
|||
|
||||
if (FileIsNotOpen(file))
|
||||
{
|
||||
while (nfile + numAllocatedFiles >= pg_nofile())
|
||||
while (nfile + numAllocatedFiles >= max_safe_fds)
|
||||
{
|
||||
if (!ReleaseLruFile())
|
||||
break;
|
||||
|
|
@ -698,7 +748,7 @@ fileNameOpenFile(FileName fileName,
|
|||
file = AllocateVfd();
|
||||
vfdP = &VfdCache[file];
|
||||
|
||||
while (nfile + numAllocatedFiles >= pg_nofile())
|
||||
while (nfile + numAllocatedFiles >= max_safe_fds)
|
||||
{
|
||||
if (!ReleaseLruFile())
|
||||
break;
|
||||
|
|
@ -1042,7 +1092,14 @@ AllocateFile(char *name, char *mode)
|
|||
|
||||
DO_DB(elog(LOG, "AllocateFile: Allocated %d", numAllocatedFiles));
|
||||
|
||||
if (numAllocatedFiles >= MAX_ALLOCATED_FILES)
|
||||
/*
|
||||
* The test against MAX_ALLOCATED_FILES prevents us from overflowing
|
||||
* allocatedFiles[]; the test against max_safe_fds prevents AllocateFile
|
||||
* from hogging every one of the available FDs, which'd lead to infinite
|
||||
* looping.
|
||||
*/
|
||||
if (numAllocatedFiles >= MAX_ALLOCATED_FILES ||
|
||||
numAllocatedFiles >= max_safe_fds - 1)
|
||||
elog(ERROR, "too many private FDs demanded");
|
||||
|
||||
TryAgain:
|
||||
|
|
|
|||
|
|
@ -10,7 +10,7 @@
|
|||
* Written by Peter Eisentraut <peter_e@gmx.net>.
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.187 2004/02/17 03:54:57 momjian Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.188 2004/02/23 20:45:59 tgl Exp $
|
||||
*
|
||||
*--------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -1102,7 +1102,7 @@ static struct config_int ConfigureNamesInt[] =
|
|||
},
|
||||
|
||||
{
|
||||
{"max_files_per_process", PGC_BACKEND, RESOURCES_KERNEL,
|
||||
{"max_files_per_process", PGC_POSTMASTER, RESOURCES_KERNEL,
|
||||
gettext_noop("Sets the maximum number of simultaneously open files for each server process."),
|
||||
NULL
|
||||
},
|
||||
|
|
|
|||
|
|
@ -7,7 +7,7 @@
|
|||
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $PostgreSQL: pgsql/src/include/storage/fd.h,v 1.42 2004/01/26 22:35:32 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/include/storage/fd.h,v 1.43 2004/02/23 20:45:59 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -71,6 +71,7 @@ extern int FreeFile(FILE *);
|
|||
extern int BasicOpenFile(FileName fileName, int fileFlags, int fileMode);
|
||||
|
||||
/* Miscellaneous support routines */
|
||||
extern void set_max_safe_fds(void);
|
||||
extern void closeAllVfds(void);
|
||||
extern void AtEOXact_Files(void);
|
||||
extern void RemovePgTempFiles(void);
|
||||
|
|
|
|||
Loading…
Reference in New Issue