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Allow using syncfs() in frontend utilities. 

This commit allows specifying a --sync-method in several frontend
utilities that must synchronize many files to disk (initdb,
pg_basebackup, pg_checksums, pg_dump, pg_rewind, and pg_upgrade).
On Linux, users can specify "syncfs" to synchronize the relevant
file systems instead of calling fsync() for every single file.  In
many cases, using syncfs() is much faster.

As with recovery_init_sync_method, this new option comes with some
caveats.  The descriptions of these caveats have been moved to a
new appendix section in the documentation.

Co-authored-by: Justin Pryzby
Reviewed-by: Michael Paquier, Thomas Munro, Robert Haas, Justin Pryzby
Discussion: https://postgr.es/m/20210930004340.GM831%40telsasoft.com
This commit is contained in:
Nathan Bossart 2023-09-06 16:27:16 -07:00
parent cccc6cdeb3
commit 8c16ad3b43
21 changed files with 271 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
doc/src/sgml/config.sgml
View File

@ -10511,15 +10511,9 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
On Linux, <literal>syncfs</literal> may be used instead, to ask the
operating system to synchronize the whole file systems that contain the
data directory, the WAL files and each tablespace (but not any other
file systems that may be reachable through symbolic links). This may
be a lot faster than the <literal>fsync</literal> setting, because it
doesn't need to open each file one by one. On the other hand, it may
be slower if a file system is shared by other applications that
modify a lot of files, since those files will also be written to disk.
Furthermore, on versions of Linux before 5.8, I/O errors encountered
while writing data to disk may not be reported to
<productname>PostgreSQL</productname>, and relevant error messages may
appear only in kernel logs.
file systems that may be reachable through symbolic links). See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
</para>
<para>
This parameter can only be set in the

1
doc/src/sgml/filelist.sgml
View File

@ -183,6 +183,7 @@
<!ENTITY acronyms SYSTEM "acronyms.sgml">
<!ENTITY glossary SYSTEM "glossary.sgml">
<!ENTITY color SYSTEM "color.sgml">
<!ENTITY syncfs SYSTEM "syncfs.sgml">
<!ENTITY features-supported SYSTEM "features-supported.sgml">
<!ENTITY features-unsupported SYSTEM "features-unsupported.sgml">

1
doc/src/sgml/postgres.sgml
View File

@ -294,6 +294,7 @@ break is not needed in a wider output rendering.
&acronyms;
&glossary;
&color;
&syncfs;
&obsolete;
</part>

22
doc/src/sgml/ref/initdb.sgml
View File

@ -365,6 +365,28 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry id="app-initdb-option-sync-method">
<term><option>--sync-method</option></term>
<listitem>
<para>
When set to <literal>fsync</literal>, which is the default,
<command>initdb</command> will recursively open and synchronize all
files in the data directory. The search for files will follow symbolic
links for the WAL directory and each configured tablespace.
</para>
<para>
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
data directory, the WAL files, and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.
</para>
</listitem>
</varlistentry>
<varlistentry id="app-initdb-option-sync-only">
<term><option>-S</option></term>
<term><option>--sync-only</option></term>

25
doc/src/sgml/ref/pg_basebackup.sgml
View File

@ -594,6 +594,31 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>--sync-method</option></term>
<listitem>
<para>
When set to <literal>fsync</literal>, which is the default,
<command>pg_basebackup</command> will recursively open and synchronize
all files in the backup directory. When the plain format is used, the
search for files will follow symbolic links for the WAL directory and
each configured tablespace.
</para>
<para>
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file system that contains the
backup directory. When the plain format is used,
<command>pg_basebackup</command> will also synchronize the file systems
that contain the WAL files and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v</option></term>
<term><option>--verbose</option></term>

22
doc/src/sgml/ref/pg_checksums.sgml
View File

@ -139,6 +139,28 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>--sync-method</option></term>
<listitem>
<para>
When set to <literal>fsync</literal>, which is the default,
<command>pg_checksums</command> will recursively open and synchronize
all files in the data directory. The search for files will follow
symbolic links for the WAL directory and each configured tablespace.
</para>
<para>
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
data directory, the WAL files, and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v</option></term>
<term><option>--verbose</option></term>

21
doc/src/sgml/ref/pg_dump.sgml
View File

@ -1179,6 +1179,27 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>--sync-method</option></term>
<listitem>
<para>
When set to <literal>fsync</literal>, which is the default,
<command>pg_dump --format=directory</command> will recursively open and
synchronize all files in the archive directory.
</para>
<para>
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file system that contains the
archive directory. See <xref linkend="syncfs"/> for more information
about using <function>syncfs()</function>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used or
<option>--format</option> is not set to <literal>directory</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--table-and-children=<replaceable class="parameter">pattern</replaceable></option></term>
<listitem>

22
doc/src/sgml/ref/pg_rewind.sgml
View File

@ -284,6 +284,28 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>--sync-method</option></term>
<listitem>
<para>
When set to <literal>fsync</literal>, which is the default,
<command>pg_rewind</command> will recursively open and synchronize all
files in the data directory. The search for files will follow symbolic
links for the WAL directory and each configured tablespace.
</para>
<para>
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
data directory, the WAL files, and each tablespace. See
<xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-V</option></term>
<term><option>--version</option></term>

23
doc/src/sgml/ref/pgupgrade.sgml
View File

@ -190,6 +190,29 @@ PostgreSQL documentation
variable <envar>PGSOCKETDIR</envar></para></listitem>
</varlistentry>
<varlistentry>
<term><option>--sync-method</option></term>
<listitem>
<para>
When set to <literal>fsync</literal>, which is the default,
<command>pg_upgrade</command> will recursively open and synchronize all
files in the upgraded cluster's data directory. The search for files
will follow symbolic links for the WAL directory and each configured
tablespace.
</para>
<para>
On Linux, <literal>syncfs</literal> may be used instead to ask the
operating system to synchronize the whole file systems that contain the
upgraded cluster's data directory, its WAL files, and each tablespace.
See <xref linkend="syncfs"/> for more information about using
<function>syncfs()</function>.
</para>
<para>
This option has no effect when <option>--no-sync</option> is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-U</option> <replaceable>username</replaceable></term>
<term><option>--username=</option><replaceable>username</replaceable></term>

36
doc/src/sgml/syncfs.sgml Normal file
View File

@ -0,0 +1,36 @@
<!-- doc/src/sgml/syncfs.sgml -->
<appendix id="syncfs">
<title><function>syncfs()</function> Caveats</title>
<indexterm zone="syncfs">
<primary>syncfs</primary>
</indexterm>
<para>
On Linux <function>syncfs()</function> may be specified for some
configuration parameters (e.g.,
<xref linkend="guc-recovery-init-sync-method"/>), server applications (e.g.,
<application>pg_upgrade</application>), and client applications (e.g.,
<application>pg_basebackup</application>) that involve synchronizing many
files to disk. <function>syncfs()</function> is advantageous in many cases,
but there are some trade-offs to keep in mind.
</para>
<para>
Since <function>syncfs()</function> instructs the operating system to
synchronize a whole file system, it typically requires many fewer system
calls than using <function>fsync()</function> to synchronize each file one by
one. Therefore, using <function>syncfs()</function> may be a lot faster than
using <function>fsync()</function>. However, it may be slower if a file
system is shared by other applications that modify a lot of files, since
those files will also be written to disk.
</para>
<para>
Furthermore, on versions of Linux before 5.8, I/O errors encountered while
writing data to disk may not be reported to the calling program, and relevant
error messages may appear only in kernel logs.
</para>
</appendix>

6
src/bin/initdb/initdb.c
View File

@ -2467,6 +2467,7 @@ usage(const char *progname)
printf(_(" -N, --no-sync do not wait for changes to be written safely to disk\n"));
printf(_(" --no-instructions do not print instructions for next steps\n"));
printf(_(" -s, --show show internal settings\n"));
printf(_(" --sync-method=METHOD set method for syncing files to disk\n"));
printf(_(" -S, --sync-only only sync database files to disk, then exit\n"));
printf(_("\nOther options:\n"));
printf(_(" -V, --version output version information, then exit\n"));
@ -3107,6 +3108,7 @@ main(int argc, char *argv[])
{"locale-provider", required_argument, NULL, 15},
{"icu-locale", required_argument, NULL, 16},
{"icu-rules", required_argument, NULL, 17},
{"sync-method", required_argument, NULL, 18},
{NULL, 0, NULL, 0}
};
@ -3287,6 +3289,10 @@ main(int argc, char *argv[])
case 17:
icu_rules = pg_strdup(optarg);
break;
case 18:
if (!parse_sync_method(optarg, &sync_method))
exit(1);
break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);

12
src/bin/initdb/t/001_initdb.pl
View File

@ -16,6 +16,7 @@ use Test::More;
my $tempdir = PostgreSQL::Test::Utils::tempdir;
my $xlogdir = "$tempdir/pgxlog";
my $datadir = "$tempdir/data";
my $supports_syncfs = check_pg_config("#define HAVE_SYNCFS 1");
program_help_ok('initdb');
program_version_ok('initdb');
@ -82,6 +83,17 @@ command_fails([ 'pg_checksums', '-D', $datadir ],
command_ok([ 'initdb', '-S', $datadir ], 'sync only');
command_fails([ 'initdb', $datadir ], 'existing data directory');
if ($supports_syncfs)
{
command_ok([ 'initdb', '-S', $datadir, '--sync-method', 'syncfs' ],
'sync method syncfs');
}
else
{
command_fails([ 'initdb', '-S', $datadir, '--sync-method', 'syncfs' ],
'sync method syncfs');
}
# Check group access on PGDATA
SKIP:
{

7
src/bin/pg_basebackup/pg_basebackup.c
View File

@ -425,6 +425,8 @@ usage(void)
printf(_(" --no-slot prevent creation of temporary replication slot\n"));
printf(_(" --no-verify-checksums\n"
" do not verify checksums\n"));
printf(_(" --sync-method=METHOD\n"
" set method for syncing files to disk\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\nConnection options:\n"));
printf(_(" -d, --dbname=CONNSTR connection string\n"));
@ -2282,6 +2284,7 @@ main(int argc, char **argv)
{"no-manifest", no_argument, NULL, 5},
{"manifest-force-encode", no_argument, NULL, 6},
{"manifest-checksums", required_argument, NULL, 7},
{"sync-method", required_argument, NULL, 8},
{NULL, 0, NULL, 0}
};
int c;
@ -2453,6 +2456,10 @@ main(int argc, char **argv)
case 7:
manifest_checksums = pg_strdup(optarg);
break;
case 8:
if (!parse_sync_method(optarg, &sync_method))
exit(1);
break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);

6
src/bin/pg_checksums/pg_checksums.c
View File

@ -78,6 +78,7 @@ usage(void)
printf(_(" -f, --filenode=FILENODE check only relation with specified filenode\n"));
printf(_(" -N, --no-sync do not wait for changes to be written safely to disk\n"));
printf(_(" -P, --progress show progress information\n"));
printf(_(" --sync-method=METHOD set method for syncing files to disk\n"));
printf(_(" -v, --verbose output verbose messages\n"));
printf(_(" -V, --version output version information, then exit\n"));
printf(_(" -?, --help show this help, then exit\n"));
@ -436,6 +437,7 @@ main(int argc, char *argv[])
{"no-sync", no_argument, NULL, 'N'},
{"progress", no_argument, NULL, 'P'},
{"verbose", no_argument, NULL, 'v'},
{"sync-method", required_argument, NULL, 1},
{NULL, 0, NULL, 0}
};
@ -494,6 +496,10 @@ main(int argc, char *argv[])
case 'v':
verbose = true;
break;
case 1:
if (!parse_sync_method(optarg, &sync_method))
exit(1);
break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);

7
src/bin/pg_dump/pg_dump.c
View File

@ -432,6 +432,7 @@ main(int argc, char **argv)
{"table-and-children", required_argument, NULL, 12},
{"exclude-table-and-children", required_argument, NULL, 13},
{"exclude-table-data-and-children", required_argument, NULL, 14},
{"sync-method", required_argument, NULL, 15},
{NULL, 0, NULL, 0}
};
@ -658,6 +659,11 @@ main(int argc, char **argv)
optarg);
break;
case 15:
if (!parse_sync_method(optarg, &sync_method))
exit_nicely(1);
break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
@ -1069,6 +1075,7 @@ help(const char *progname)
" compress as specified\n"));
printf(_(" --lock-wait-timeout=TIMEOUT fail after waiting TIMEOUT for a table lock\n"));
printf(_(" --no-sync do not wait for changes to be written safely to disk\n"));
printf(_(" --sync-method=METHOD set method for syncing files to disk\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\nOptions controlling the output content:\n"));

8
src/bin/pg_rewind/pg_rewind.c
View File

@ -22,6 +22,7 @@
#include "common/file_perm.h"
#include "common/restricted_token.h"
#include "common/string.h"
#include "fe_utils/option_utils.h"
#include "fe_utils/recovery_gen.h"
#include "fe_utils/string_utils.h"
#include "file_ops.h"
@ -108,6 +109,7 @@ usage(const char *progname)
" file when running target cluster\n"));
printf(_(" --debug write a lot of debug messages\n"));
printf(_(" --no-ensure-shutdown do not automatically fix unclean shutdown\n"));
printf(_(" --sync-method=METHOD set method for syncing files to disk\n"));
printf(_(" -V, --version output version information, then exit\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
@ -132,6 +134,7 @@ main(int argc, char **argv)
{"no-sync", no_argument, NULL, 'N'},
{"progress", no_argument, NULL, 'P'},
{"debug", no_argument, NULL, 3},
{"sync-method", required_argument, NULL, 6},
{NULL, 0, NULL, 0}
};
int option_index;
@ -219,6 +222,11 @@ main(int argc, char **argv)
config_file = pg_strdup(optarg);
break;
case 6:
if (!parse_sync_method(optarg, &sync_method))
exit(1);
break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);

13
src/bin/pg_upgrade/option.c
View File

@ -14,6 +14,7 @@
#endif
#include "common/string.h"
#include "fe_utils/option_utils.h"
#include "getopt_long.h"
#include "pg_upgrade.h"
#include "utils/pidfile.h"
@ -57,12 +58,14 @@ parseCommandLine(int argc, char *argv[])
{"verbose", no_argument, NULL, 'v'},
{"clone", no_argument, NULL, 1},
{"copy", no_argument, NULL, 2},
{"sync-method", required_argument, NULL, 3},
{NULL, 0, NULL, 0}
};
int option; /* Command line option */
int optindex = 0; /* used by getopt_long */
int os_user_effective_id;
DataDirSyncMethod unused;
user_opts.do_sync = true;
user_opts.transfer_mode = TRANSFER_MODE_COPY;
@ -199,6 +202,12 @@ parseCommandLine(int argc, char *argv[])
user_opts.transfer_mode = TRANSFER_MODE_COPY;
break;
case 3:
if (!parse_sync_method(optarg, &unused))
exit(1);
user_opts.sync_method = pg_strdup(optarg);
break;
default:
fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
os_info.progname);
@ -209,6 +218,9 @@ parseCommandLine(int argc, char *argv[])
if (optind < argc)
pg_fatal("too many command-line arguments (first is \"%s\")", argv[optind]);
if (!user_opts.sync_method)
user_opts.sync_method = pg_strdup("fsync");
if (log_opts.verbose)
pg_log(PG_REPORT, "Running in verbose mode");
@ -289,6 +301,7 @@ usage(void)
printf(_(" -V, --version display version information, then exit\n"));
printf(_(" --clone clone instead of copying files to new cluster\n"));
printf(_(" --copy copy files to new cluster (default)\n"));
printf(_(" --sync-method=METHOD set method for syncing files to disk\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\n"
"Before running pg_upgrade you must:\n"

6
src/bin/pg_upgrade/pg_upgrade.c
View File

@ -192,8 +192,10 @@ main(int argc, char **argv)
{
prep_status("Sync data directory to disk");
exec_prog(UTILITY_LOG_FILE, NULL, true, true,
"\"%s/initdb\" --sync-only \"%s\"", new_cluster.bindir,
new_cluster.pgdata);
"\"%s/initdb\" --sync-only \"%s\" --sync-method %s",
new_cluster.bindir,
new_cluster.pgdata,
user_opts.sync_method);
check_ok();
}

1
src/bin/pg_upgrade/pg_upgrade.h
View File

@ -304,6 +304,7 @@ typedef struct
transferMode transfer_mode; /* copy files or link them? */
int jobs; /* number of processes/threads to use */
char *socketdir; /* directory to use for Unix sockets */
char *sync_method;
} UserOpts;
typedef struct

27
src/fe_utils/option_utils.c
View File

@ -82,3 +82,30 @@ option_parse_int(const char *optarg, const char *optname,
*result = val;
return true;
}
/*
* Provide strictly harmonized handling of the --sync-method option.
*/
bool
parse_sync_method(const char *optarg, DataDirSyncMethod *sync_method)
{
if (strcmp(optarg, "fsync") == 0)
*sync_method = DATA_DIR_SYNC_METHOD_FSYNC;
else if (strcmp(optarg, "syncfs") == 0)
{
#ifdef HAVE_SYNCFS
*sync_method = DATA_DIR_SYNC_METHOD_SYNCFS;
#else
pg_log_error("this build does not support sync method \"%s\"",
"syncfs");
return false;
#endif
}
else
{
pg_log_error("unrecognized sync method: %s", optarg);
return false;
}
return true;
}

4
src/include/fe_utils/option_utils.h
View File

@ -14,6 +14,8 @@
#include "postgres_fe.h"
#include "common/file_utils.h"
typedef void (*help_handler) (const char *progname);
extern void handle_help_version_opts(int argc, char *argv[],
@ -22,5 +24,7 @@ extern void handle_help_version_opts(int argc, char *argv[],
extern bool option_parse_int(const char *optarg, const char *optname,
int min_range, int max_range,
int *result);
extern bool parse_sync_method(const char *optarg,
DataDirSyncMethod *sync_method);
#endif /* OPTION_UTILS_H */