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Allow parallel zstd compression when taking a base backup. 

libzstd allows transparent parallel compression just by setting
an option when creating the compression context, so permit that
for both client and server-side backup compression. To use this,
use something like pg_basebackup --compress WHERE-zstd:workers=N
where WHERE is "client" or "server" and N is an integer.

When compression is performed on the server side, this will spawn
threads inside the PostgreSQL backend. While there is almost no
PostgreSQL server code which is thread-safe, the threads here are used
internally by libzstd and touch only data structures controlled by
libzstd.

Patch by me, based in part on earlier work by Dipesh Pandit
and Jeevan Ladhe. Reviewed by Justin Pryzby.

Discussion: http://postgr.es/m/CA+Tgmobj6u-nWF-j=FemygUhobhryLxf9h-wJN7W-2rSsseHNA@mail.gmail.com
This commit is contained in:
Robert Haas 2022-03-30 09:35:14 -04:00
parent c6863b8582
commit 51c0d186d9
9 changed files with 147 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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

@ -2739,17 +2739,23 @@ The commands accepted in replication mode are:
option. If the value is an integer, it specifies the compression
level. Otherwise, it should be a comma-separated list of items,
each of the form <literal>keyword</literal> or
<literal>keyword=value</literal>. Currently, the only supported
keyword is <literal>level</literal>, which sets the compression
level.
<literal>keyword=value</literal>. Currently, the supported keywords
are <literal>level</literal> and <literal>workers</literal>.
</para>
<para>
The <literal>level</literal> keyword sets the compression level.
For <literal>gzip</literal> the compression level should be an
integer between 1 and 9, for <literal>lz4</literal> an integer
between 1 and 12, and for <literal>zstd</literal> an integer
between 1 and 22.
</para>
<para>
The <literal>workers</literal> keyword sets the number of threads
that should be used for parallel compression. Parallel compression
is supported only for <literal>zstd</literal>.
</para>
</listitem>
</varlistentry>

4
doc/src/sgml/ref/pg_basebackup.sgml
View File

@ -424,8 +424,8 @@ PostgreSQL documentation
integer, it specifies the compression level. Otherwise, it should be
a comma-separated list of items, each of the form
<literal>keyword</literal> or <literal>keyword=value</literal>.
Currently, the only supported keyword is <literal>level</literal>,
which sets the compression level.
Currently, the supported keywords are <literal>level</literal>
and <literal>workers</literal>.
</para>
<para>
If no compression level is specified, the default compression level

45
src/backend/replication/basebackup_zstd.c
View File

@ -25,8 +25,8 @@ typedef struct bbsink_zstd
/* Common information for all types of sink. */
bbsink base;
/* Compression level */
int compresslevel;
/* Compression options */
bc_specification *compress;
ZSTD_CCtx *cctx;
ZSTD_outBuffer zstd_outBuf;
@ -67,22 +67,13 @@ bbsink_zstd_new(bbsink *next, bc_specification *compress)
return NULL; /* keep compiler quiet */
#else
bbsink_zstd *sink;
int compresslevel;
Assert(next != NULL);
if ((compress->options & BACKUP_COMPRESSION_OPTION_LEVEL) == 0)
compresslevel = 0;
else
{
compresslevel = compress->level;
Assert(compresslevel >= 1 && compresslevel <= 22);
}
sink = palloc0(sizeof(bbsink_zstd));
*((const bbsink_ops **) &sink->base.bbs_ops) = &bbsink_zstd_ops;
sink->base.bbs_next = next;
sink->compresslevel = compresslevel;
sink->compress = compress;
return &sink->base;
#endif
@ -99,16 +90,36 @@ bbsink_zstd_begin_backup(bbsink *sink)
bbsink_zstd *mysink = (bbsink_zstd *) sink;
size_t output_buffer_bound;
size_t ret;
bc_specification *compress = mysink->compress;
mysink->cctx = ZSTD_createCCtx();
if (!mysink->cctx)
elog(ERROR, "could not create zstd compression context");
ret = ZSTD_CCtx_setParameter(mysink->cctx, ZSTD_c_compressionLevel,
mysink->compresslevel);
if (ZSTD_isError(ret))
elog(ERROR, "could not set zstd compression level to %d: %s",
mysink->compresslevel, ZSTD_getErrorName(ret));
if ((compress->options & BACKUP_COMPRESSION_OPTION_LEVEL) != 0)
{
ret = ZSTD_CCtx_setParameter(mysink->cctx, ZSTD_c_compressionLevel,
compress->level);
if (ZSTD_isError(ret))
elog(ERROR, "could not set zstd compression level to %d: %s",
compress->level, ZSTD_getErrorName(ret));
}
if ((compress->options & BACKUP_COMPRESSION_OPTION_WORKERS) != 0)
{
/*
* On older versions of libzstd, this option does not exist, and trying
* to set it will fail. Similarly for newer versions if they are
* compiled without threading support.
*/
ret = ZSTD_CCtx_setParameter(mysink->cctx, ZSTD_c_nbWorkers,
compress->workers);
if (ZSTD_isError(ret))
ereport(ERROR,
errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not set compression worker count to %d: %s",
compress->workers, ZSTD_getErrorName(ret)));
}
/*
* We need our own buffer, because we're going to pass different data to

40
src/bin/pg_basebackup/bbstreamer_zstd.c
View File

@ -67,7 +67,6 @@ bbstreamer_zstd_compressor_new(bbstreamer *next, bc_specification *compress)
{
#ifdef USE_ZSTD
bbstreamer_zstd_frame *streamer;
int compresslevel;
size_t ret;
Assert(next != NULL);
@ -88,18 +87,35 @@ bbstreamer_zstd_compressor_new(bbstreamer *next, bc_specification *compress)
exit(1);
}
/* Initialize stream compression preferences */
if ((compress->options & BACKUP_COMPRESSION_OPTION_LEVEL) == 0)
compresslevel = 0;
else
compresslevel = compress->level;
ret = ZSTD_CCtx_setParameter(streamer->cctx, ZSTD_c_compressionLevel,
compresslevel);
if (ZSTD_isError(ret))
/* Set compression level, if specified */
if ((compress->options & BACKUP_COMPRESSION_OPTION_LEVEL) != 0)
{
pg_log_error("could not set zstd compression level to %d: %s",
compresslevel, ZSTD_getErrorName(ret));
exit(1);
ret = ZSTD_CCtx_setParameter(streamer->cctx, ZSTD_c_compressionLevel,
compress->level);
if (ZSTD_isError(ret))
{
pg_log_error("could not set zstd compression level to %d: %s",
compress->level, ZSTD_getErrorName(ret));
exit(1);
}
}
/* Set # of workers, if specified */
if ((compress->options & BACKUP_COMPRESSION_OPTION_WORKERS) != 0)
{
/*
* On older versions of libzstd, this option does not exist, and
* trying to set it will fail. Similarly for newer versions if they
* are compiled without threading support.
*/
ret = ZSTD_CCtx_setParameter(streamer->cctx, ZSTD_c_nbWorkers,
compress->workers);
if (ZSTD_isError(ret))
{
pg_log_error("could not set compression worker count to %d: %s",
compress->workers, ZSTD_getErrorName(ret));
exit(1);
}
}
/* Initialize the ZSTD output buffer. */

5
src/bin/pg_basebackup/t/010_pg_basebackup.pl
View File

@ -130,6 +130,11 @@ my @compression_failure_tests = (
'invalid compression specification: found empty string where a compression option was expected',
'failure on extra, empty compression option'
],
[
'gzip:workers=3',
'invalid compression specification: compression algorithm "gzip" does not accept a worker count',
'failure on worker count for gzip'
],
);
for my $cft (@compression_failure_tests)
{

29
src/bin/pg_verifybackup/t/009_extract.pl
View File

@ -34,6 +34,12 @@ my @test_configuration = (
'compression_method' => 'zstd',
'backup_flags' => ['--compress', 'server-zstd:5'],
'enabled' => check_pg_config("#define USE_ZSTD 1")
},
{
'compression_method' => 'parallel zstd',
'backup_flags' => ['--compress', 'server-zstd:workers=3'],
'enabled' => check_pg_config("#define USE_ZSTD 1"),
'possibly_unsupported' => qr/could not set compression worker count to 3: Unsupported parameter/
}
);
@ -55,8 +61,27 @@ for my $tc (@test_configuration)
my @verify = ('pg_verifybackup', '-e', $backup_path);
# A backup with a valid compression method should work.
$primary->command_ok(\@backup,
"backup done, compression method \"$method\"");
my $backup_stdout = '';
my $backup_stderr = '';
my $backup_result = $primary->run_log(\@backup, '>', \$backup_stdout,
'2>', \$backup_stderr);
if ($backup_stdout ne '')
{
print "# standard output was:\n$backup_stdout";
}
if ($backup_stderr ne '')
{
print "# standard error was:\n$backup_stderr";
}
if (! $backup_result && $tc->{'possibly_unsupported'} &&
$backup_stderr =~ /$tc->{'possibly_unsupported'}/)
{
skip "compression with $method not supported by this build", 2;
}
else
{
ok($backup_result, "backup done, compression $method");
}
# Make sure that it verifies OK.
$primary->command_ok(\@verify,

33
src/bin/pg_verifybackup/t/010_client_untar.pl
View File

@ -49,6 +49,15 @@ my @test_configuration = (
'decompress_program' => $ENV{'ZSTD'},
'decompress_flags' => [ '-d' ],
'enabled' => check_pg_config("#define USE_ZSTD 1")
},
{
'compression_method' => 'parallel zstd',
'backup_flags' => ['--compress', 'client-zstd:workers=3'],
'backup_archive' => 'base.tar.zst',
'decompress_program' => $ENV{'ZSTD'},
'decompress_flags' => [ '-d' ],
'enabled' => check_pg_config("#define USE_ZSTD 1"),
'possibly_unsupported' => qr/could not set compression worker count to 3: Unsupported parameter/
}
);
@ -69,9 +78,27 @@ for my $tc (@test_configuration)
'pg_basebackup', '-D', $backup_path,
'-Xfetch', '--no-sync', '-cfast', '-Ft');
push @backup, @{$tc->{'backup_flags'}};
$primary->command_ok(\@backup,
"client side backup, compression $method");
my $backup_stdout = '';
my $backup_stderr = '';
my $backup_result = $primary->run_log(\@backup, '>', \$backup_stdout,
'2>', \$backup_stderr);
if ($backup_stdout ne '')
{
print "# standard output was:\n$backup_stdout";
}
if ($backup_stderr ne '')
{
print "# standard error was:\n$backup_stderr";
}
if (! $backup_result && $tc->{'possibly_unsupported'} &&
$backup_stderr =~ /$tc->{'possibly_unsupported'}/)
{
skip "compression with $method not supported by this build", 3;
}
else
{
ok($backup_result, "client side backup, compression $method");
}
# Verify that the we got the files we expected.
my $backup_files = join(',',

16
src/common/backup_compression.c
View File

@ -177,6 +177,11 @@ parse_bc_specification(bc_algorithm algorithm, char *specification,
result->level = expect_integer_value(keyword, value, result);
result->options |= BACKUP_COMPRESSION_OPTION_LEVEL;
}
else if (strcmp(keyword, "workers") == 0)
{
result->workers = expect_integer_value(keyword, value, result);
result->options |= BACKUP_COMPRESSION_OPTION_WORKERS;
}
else
result->parse_error =
psprintf(_("unknown compression option \"%s\""), keyword);
@ -266,5 +271,16 @@ validate_bc_specification(bc_specification *spec)
min_level, max_level);
}
/*
* Of the compression algorithms that we currently support, only zstd
* allows parallel workers.
*/
if ((spec->options & BACKUP_COMPRESSION_OPTION_WORKERS) != 0 &&
(spec->algorithm != BACKUP_COMPRESSION_ZSTD))
{
return psprintf(_("compression algorithm \"%s\" does not accept a worker count"),
get_bc_algorithm_name(spec->algorithm));
}
return NULL;
}

2
src/include/common/backup_compression.h
View File

@ -23,12 +23,14 @@ typedef enum bc_algorithm
} bc_algorithm;
#define BACKUP_COMPRESSION_OPTION_LEVEL (1 << 0)
#define BACKUP_COMPRESSION_OPTION_WORKERS (1 << 1)
typedef struct bc_specification
{
bc_algorithm algorithm;
unsigned options; /* OR of BACKUP_COMPRESSION_OPTION constants */
int level;
int workers;
char *parse_error; /* NULL if parsing was OK, else message */
} bc_specification;