Thanks for reviewing the patch!
On Thu, Nov 13, 2014 at 4:05 AM, Alvaro Herrera
<alvhe...@2ndquadrant.com> wrote:
> Fujii Masao wrote:
>
>> --- 127,152 ----
>> When this option is used, <application>pg_receivexlog</> will
>> report
>> a flush position to the server, indicating when each segment has
>> been
>> synchronized to disk so that the server can remove that segment
>> if it
>> ! is not otherwise needed. <literal>--synchronous</literal> option
>> must
>> ! be specified when making <application>pg_receivexlog</> run as
>> ! synchronous standby by using replication slot. Otherwise WAL data
>> ! cannot be flushed frequently enough for this to work correctly.
>> </para>
>> </listitem>
>> </varlistentry>
>
> Whitespace damage here.
Fixed.
>> + printf(_(" --synchronous flush transaction log in real
>> time\n"));
>
> "in real time" sounds odd. How about "flush transaction log
> immediately after writing", or maybe "have transaction log writes be
> synchronous".
The former sounds better to me. So I chose it.
>> --- 781,791 ----
>> now = feGetCurrentTimestamp();
>>
>> /*
>> ! * Issue sync command as soon as there are WAL data which
>> ! * has not been flushed yet if synchronous option is true.
>> */
>> if (lastFlushPosition < blockpos &&
>> ! walfile != -1 && synchronous)
>
> I'd put the "synchronous" condition first in the if(), and start the
> comment with it rather than putting it at the end. Both seem weird.
Fixed, i.e., moved the "synchronous" condition first in the if()'s test
and also moved the comment "If synchronous option is true" also first
in the comment.
>> progname,
>> current_walfile_name, strerror(errno));
>> goto error;
>> }
>> lastFlushPosition = blockpos;
>> !
>> ! /*
>> ! * Send feedback so that the server sees the latest
>> WAL locations
>> ! * immediately if synchronous option is true.
>> ! */
>> ! if (!sendFeedback(conn, blockpos, now, false))
>> ! goto error;
>> ! last_status = now;
>
> I'm not clear about this comment .. why does it say "if synchronous
> option is true" when it's not checking the condition?
I added that comment because the code exists with the if() block
checking "synchronous" condition. But it seems confusing. Just removed
that part from the comment.
Attached is the updated version of the patch.
Regards,
--
Fujii Masao
*** a/doc/src/sgml/ref/pg_receivexlog.sgml
--- b/doc/src/sgml/ref/pg_receivexlog.sgml
***************
*** 49,54 **** PostgreSQL documentation
--- 49,61 ----
</para>
<para>
+ Unlike the standby's WAL receiver, <application>pg_receivexlog</>
+ flushes WAL data only when WAL file is closed, by default.
+ <literal>--synchronous</> option must be specified to flush WAL data
+ in real time and ensure it's safely flushed to disk.
+ </para>
+
+ <para>
The transaction log is streamed over a regular
<productname>PostgreSQL</productname> connection, and uses the replication
protocol. The connection must be made with a superuser or a user
***************
*** 86,106 **** PostgreSQL documentation
</varlistentry>
<varlistentry>
- <term><option>-F <replaceable class="parameter">interval</replaceable></option></term>
- <term><option>--fsync-interval=<replaceable class="parameter">interval</replaceable></option></term>
- <listitem>
- <para>
- Specifies the maximum time to issue sync commands to ensure the
- received WAL file is safely flushed to disk, in seconds. The default
- value is zero, which disables issuing fsyncs except when WAL file is
- closed. If <literal>-1</literal> is specified, WAL file is flushed as
- soon as possible, that is, as soon as there are WAL data which has
- not been flushed yet.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
<term><option>-n</option></term>
<term><option>--no-loop</option></term>
<listitem>
--- 93,98 ----
***************
*** 135,150 **** PostgreSQL documentation
When this option is used, <application>pg_receivexlog</> will report
a flush position to the server, indicating when each segment has been
synchronized to disk so that the server can remove that segment if it
! is not otherwise needed. When using this parameter, it is important
! to make sure that <application>pg_receivexlog</> cannot become the
! synchronous standby through an incautious setting of
! <xref linkend="guc-synchronous-standby-names">; it does not flush
! data frequently enough for this to work correctly.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v</option></term>
<term><option>--verbose</option></term>
<listitem>
--- 127,152 ----
When this option is used, <application>pg_receivexlog</> will report
a flush position to the server, indicating when each segment has been
synchronized to disk so that the server can remove that segment if it
! is not otherwise needed. <literal>--synchronous</literal> option must
! be specified when making <application>pg_receivexlog</> run as
! synchronous standby by using replication slot. Otherwise WAL data
! cannot be flushed frequently enough for this to work correctly.
</para>
</listitem>
</varlistentry>
<varlistentry>
+ <term><option>--synchronous</option></term>
+ <listitem>
+ <para>
+ Issue sync commands as soon as there is WAL data which has not been
+ flushed yet. Also status packets are sent back to the server just after
+ WAL data is flushed whatever <literal>--status-interval</> is set to.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
<term><option>-v</option></term>
<term><option>--verbose</option></term>
<listitem>
*** a/src/bin/pg_basebackup/pg_basebackup.c
--- b/src/bin/pg_basebackup/pg_basebackup.c
***************
*** 370,376 **** LogStreamerMain(logstreamer_param *param)
if (!ReceiveXlogStream(param->bgconn, param->startptr, param->timeline,
param->sysidentifier, param->xlogdir,
reached_end_position, standby_message_timeout,
! NULL, 0))
/*
* Any errors will already have been reported in the function process,
--- 370,376 ----
if (!ReceiveXlogStream(param->bgconn, param->startptr, param->timeline,
param->sysidentifier, param->xlogdir,
reached_end_position, standby_message_timeout,
! NULL, false))
/*
* Any errors will already have been reported in the function process,
*** a/src/bin/pg_basebackup/pg_receivexlog.c
--- b/src/bin/pg_basebackup/pg_receivexlog.c
***************
*** 36,45 **** static char *basedir = NULL;
static int verbose = 0;
static int noloop = 0;
static int standby_message_timeout = 10 * 1000; /* 10 sec = default */
- static int fsync_interval = 0; /* 0 = default */
static volatile bool time_to_abort = false;
static bool do_create_slot = false;
static bool do_drop_slot = false;
static void usage(void);
--- 36,45 ----
static int verbose = 0;
static int noloop = 0;
static int standby_message_timeout = 10 * 1000; /* 10 sec = default */
static volatile bool time_to_abort = false;
static bool do_create_slot = false;
static bool do_drop_slot = false;
+ static bool synchronous = false;
static void usage(void);
***************
*** 66,77 **** usage(void)
printf(_(" %s [OPTION]...\n"), progname);
printf(_("\nOptions:\n"));
printf(_(" -D, --directory=DIR receive transaction log files into this directory\n"));
- printf(_(" -F --fsync-interval=SECS\n"
- " time between fsyncs to transaction log files (default: %d)\n"), (fsync_interval / 1000));
printf(_(" -n, --no-loop do not loop on connection lost\n"));
printf(_(" -s, --status-interval=SECS\n"
" time between status packets sent to server (default: %d)\n"), (standby_message_timeout / 1000));
printf(_(" -S, --slot=SLOTNAME replication slot to use\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"));
--- 66,76 ----
printf(_(" %s [OPTION]...\n"), progname);
printf(_("\nOptions:\n"));
printf(_(" -D, --directory=DIR receive transaction log files into this directory\n"));
printf(_(" -n, --no-loop do not loop on connection lost\n"));
printf(_(" -s, --status-interval=SECS\n"
" time between status packets sent to server (default: %d)\n"), (standby_message_timeout / 1000));
printf(_(" -S, --slot=SLOTNAME replication slot to use\n"));
+ printf(_(" --synchronous flush transaction log immediately after writing\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"));
***************
*** 343,349 **** StreamLog(void)
ReceiveXlogStream(conn, startpos, starttli, NULL, basedir,
stop_streaming, standby_message_timeout, ".partial",
! fsync_interval);
PQfinish(conn);
conn = NULL;
--- 342,348 ----
ReceiveXlogStream(conn, startpos, starttli, NULL, basedir,
stop_streaming, standby_message_timeout, ".partial",
! synchronous);
PQfinish(conn);
conn = NULL;
***************
*** 374,380 **** main(int argc, char **argv)
{"port", required_argument, NULL, 'p'},
{"username", required_argument, NULL, 'U'},
{"no-loop", no_argument, NULL, 'n'},
- {"fsync-interval", required_argument, NULL, 'F'},
{"no-password", no_argument, NULL, 'w'},
{"password", no_argument, NULL, 'W'},
{"status-interval", required_argument, NULL, 's'},
--- 373,378 ----
***************
*** 383,388 **** main(int argc, char **argv)
--- 381,387 ----
/* action */
{"create-slot", no_argument, NULL, 1},
{"drop-slot", no_argument, NULL, 2},
+ {"synchronous", no_argument, NULL, 3},
{NULL, 0, NULL, 0}
};
***************
*** 408,414 **** main(int argc, char **argv)
}
}
! while ((c = getopt_long(argc, argv, "D:d:h:p:U:s:S:nF:wWv",
long_options, &option_index)) != -1)
{
switch (c)
--- 407,413 ----
}
}
! while ((c = getopt_long(argc, argv, "D:d:h:p:U:s:S:nwWv",
long_options, &option_index)) != -1)
{
switch (c)
***************
*** 455,469 **** main(int argc, char **argv)
case 'n':
noloop = 1;
break;
- case 'F':
- fsync_interval = atoi(optarg) * 1000;
- if (fsync_interval < -1000)
- {
- fprintf(stderr, _("%s: invalid fsync interval \"%s\"\n"),
- progname, optarg);
- exit(1);
- }
- break;
case 'v':
verbose++;
break;
--- 454,459 ----
***************
*** 474,479 **** main(int argc, char **argv)
--- 464,472 ----
case 2:
do_drop_slot = true;
break;
+ case 3:
+ synchronous = true;
+ break;
default:
/*
*** a/src/bin/pg_basebackup/receivelog.c
--- b/src/bin/pg_basebackup/receivelog.c
***************
*** 31,44 **** static char current_walfile_name[MAXPGPATH] = "";
static bool reportFlushPosition = false;
static XLogRecPtr lastFlushPosition = InvalidXLogRecPtr;
- static int64 last_fsync = -1; /* timestamp of last WAL file flush */
static bool still_sending = true; /* feedback still needs to be sent? */
static PGresult *HandleCopyStream(PGconn *conn, XLogRecPtr startpos,
uint32 timeline, char *basedir,
stream_stop_callback stream_stop, int standby_message_timeout,
char *partial_suffix, XLogRecPtr *stoppos,
! int fsync_interval);
static int CopyStreamPoll(PGconn *conn, long timeout_ms);
static int CopyStreamReceive(PGconn *conn, long timeout, char **buffer);
static bool ProcessKeepaliveMsg(PGconn *conn, char *copybuf, int len,
--- 31,43 ----
static bool reportFlushPosition = false;
static XLogRecPtr lastFlushPosition = InvalidXLogRecPtr;
static bool still_sending = true; /* feedback still needs to be sent? */
static PGresult *HandleCopyStream(PGconn *conn, XLogRecPtr startpos,
uint32 timeline, char *basedir,
stream_stop_callback stream_stop, int standby_message_timeout,
char *partial_suffix, XLogRecPtr *stoppos,
! bool synchronous);
static int CopyStreamPoll(PGconn *conn, long timeout_ms);
static int CopyStreamReceive(PGconn *conn, long timeout, char **buffer);
static bool ProcessKeepaliveMsg(PGconn *conn, char *copybuf, int len,
***************
*** 55,62 **** static bool CheckCopyStreamStop(PGconn *conn, XLogRecPtr blockpos,
stream_stop_callback stream_stop,
char *partial_suffix, XLogRecPtr *stoppos);
static long CalculateCopyStreamSleeptime(int64 now, int standby_message_timeout,
! int64 last_status, int fsync_interval,
! XLogRecPtr blockpos);
static bool ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos,
uint32 *timeline);
--- 54,60 ----
stream_stop_callback stream_stop,
char *partial_suffix, XLogRecPtr *stoppos);
static long CalculateCopyStreamSleeptime(int64 now, int standby_message_timeout,
! int64 last_status);
static bool ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos,
uint32 *timeline);
***************
*** 209,215 **** close_walfile(char *basedir, char *partial_suffix, XLogRecPtr pos)
progname, current_walfile_name, partial_suffix);
lastFlushPosition = pos;
- last_fsync = feGetCurrentTimestamp();
return true;
}
--- 207,212 ----
***************
*** 440,447 **** CheckServerVersionForStreaming(PGconn *conn)
* allows you to tell the difference between partial and completed files,
* so that you can continue later where you left.
*
! * fsync_interval controls how often we flush to the received WAL file,
! * in milliseconds.
*
* Note: The log position *must* be at a log segment start!
*/
--- 437,444 ----
* allows you to tell the difference between partial and completed files,
* so that you can continue later where you left.
*
! * If 'synchronous' is true, the received WAL is flushed as soon as written,
! * otherwise only when the WAL file is closed.
*
* Note: The log position *must* be at a log segment start!
*/
***************
*** 450,456 **** ReceiveXlogStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
char *sysidentifier, char *basedir,
stream_stop_callback stream_stop,
int standby_message_timeout, char *partial_suffix,
! int fsync_interval)
{
char query[128];
char slotcmd[128];
--- 447,453 ----
char *sysidentifier, char *basedir,
stream_stop_callback stream_stop,
int standby_message_timeout, char *partial_suffix,
! bool synchronous)
{
char query[128];
char slotcmd[128];
***************
*** 595,601 **** ReceiveXlogStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
/* Stream the WAL */
res = HandleCopyStream(conn, startpos, timeline, basedir, stream_stop,
standby_message_timeout, partial_suffix,
! &stoppos, fsync_interval);
if (res == NULL)
goto error;
--- 592,598 ----
/* Stream the WAL */
res = HandleCopyStream(conn, startpos, timeline, basedir, stream_stop,
standby_message_timeout, partial_suffix,
! &stoppos, synchronous);
if (res == NULL)
goto error;
***************
*** 760,766 **** static PGresult *
HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
char *basedir, stream_stop_callback stream_stop,
int standby_message_timeout, char *partial_suffix,
! XLogRecPtr *stoppos, int fsync_interval)
{
char *copybuf = NULL;
int64 last_status = -1;
--- 757,763 ----
HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
char *basedir, stream_stop_callback stream_stop,
int standby_message_timeout, char *partial_suffix,
! XLogRecPtr *stoppos, bool synchronous)
{
char *copybuf = NULL;
int64 last_status = -1;
***************
*** 784,797 **** HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
now = feGetCurrentTimestamp();
/*
! * If fsync_interval has elapsed since last WAL flush and we've written
! * some WAL data, flush them to disk.
*/
! if (lastFlushPosition < blockpos &&
! walfile != -1 &&
! ((fsync_interval > 0 &&
! feTimestampDifferenceExceeds(last_fsync, now, fsync_interval)) ||
! fsync_interval < 0))
{
if (fsync(walfile) != 0)
{
--- 781,790 ----
now = feGetCurrentTimestamp();
/*
! * If synchronous option is true, issue sync command as soon as
! * there are WAL data which has not been flushed yet.
*/
! if (synchronous && lastFlushPosition < blockpos && walfile != -1)
{
if (fsync(walfile) != 0)
{
***************
*** 799,807 **** HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
progname, current_walfile_name, strerror(errno));
goto error;
}
-
lastFlushPosition = blockpos;
! last_fsync = now;
}
/*
--- 792,806 ----
progname, current_walfile_name, strerror(errno));
goto error;
}
lastFlushPosition = blockpos;
!
! /*
! * Send feedback so that the server sees the latest WAL locations
! * immediately.
! */
! if (!sendFeedback(conn, blockpos, now, false))
! goto error;
! last_status = now;
}
/*
***************
*** 821,827 **** HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
* Calculate how long send/receive loops should sleep
*/
sleeptime = CalculateCopyStreamSleeptime(now, standby_message_timeout,
! last_status, fsync_interval, blockpos);
r = CopyStreamReceive(conn, sleeptime, ©buf);
while (r != 0)
--- 820,826 ----
* Calculate how long send/receive loops should sleep
*/
sleeptime = CalculateCopyStreamSleeptime(now, standby_message_timeout,
! last_status);
r = CopyStreamReceive(conn, sleeptime, ©buf);
while (r != 0)
***************
*** 1244,1277 **** CheckCopyStreamStop(PGconn *conn, XLogRecPtr blockpos, uint32 timeline,
*/
static long
CalculateCopyStreamSleeptime(int64 now, int standby_message_timeout,
! int64 last_status, int fsync_interval, XLogRecPtr blockpos)
{
- int64 targettime = 0;
int64 status_targettime = 0;
- int64 fsync_targettime = 0;
long sleeptime;
if (standby_message_timeout && still_sending)
status_targettime = last_status +
(standby_message_timeout - 1) * ((int64) 1000);
! if (fsync_interval > 0 && lastFlushPosition < blockpos)
! fsync_targettime = last_fsync +
! (fsync_interval - 1) * ((int64) 1000);
!
! if ((status_targettime < fsync_targettime && status_targettime > 0) ||
! fsync_targettime == 0)
! targettime = status_targettime;
! else
! targettime = fsync_targettime;
!
! if (targettime > 0)
{
long secs;
int usecs;
feTimestampDifference(now,
! targettime,
&secs,
&usecs);
/* Always sleep at least 1 sec */
--- 1243,1264 ----
*/
static long
CalculateCopyStreamSleeptime(int64 now, int standby_message_timeout,
! int64 last_status)
{
int64 status_targettime = 0;
long sleeptime;
if (standby_message_timeout && still_sending)
status_targettime = last_status +
(standby_message_timeout - 1) * ((int64) 1000);
! if (status_targettime > 0)
{
long secs;
int usecs;
feTimestampDifference(now,
! status_targettime,
&secs,
&usecs);
/* Always sleep at least 1 sec */
*** a/src/bin/pg_basebackup/receivelog.h
--- b/src/bin/pg_basebackup/receivelog.h
***************
*** 31,36 **** extern bool ReceiveXlogStream(PGconn *conn,
stream_stop_callback stream_stop,
int standby_message_timeout,
char *partial_suffix,
! int fsync_interval);
#endif /* RECEIVELOG_H */
--- 31,36 ----
stream_stop_callback stream_stop,
int standby_message_timeout,
char *partial_suffix,
! bool synchronous);
#endif /* RECEIVELOG_H */
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