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Don't pay heed to wal_sender_timeout while creating a decoding slot.

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Sometimes CREATE_REPLICATION_SLOT ... LOGICAL ... needs to wait for
further WAL using WalSndWaitForWal(). That used to always respect
wal_sender_timeout and kill the session when waiting long enough
because no feedback/ping messages can be sent while the slot is still
being created.
Introduce the notion that last_reply_timestamp = 0 means that the
walsender currently doesn't need timeout processing to avoid that
problem. Use that notion for CREATE_REPLICATION_SLOT ... LOGICAL.

Bugreport and initial patch by Steve Singer, revised by me.
This commit is contained in:
Andres Freund 2014-05-29 00:32:09 +02:00
parent d1d50bff24
commit 21d48d66c8
1 changed files with 26 additions and 5 deletions
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31
src/backend/replication/walsender.c
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@ -148,9 +148,10 @@ static StringInfoData reply_message;
static StringInfoData tmpbuf; static StringInfoData tmpbuf;
/* /*
* Timestamp of the last receipt of the reply from the standby. * Timestamp of the last receipt of the reply from the standby. Set to 0 if
* wal_sender_timeout doesn't need to be active.
*/ */
static TimestampTz last_reply_timestamp; static TimestampTz last_reply_timestamp = 0;
/* Have we sent a heartbeat message asking for reply, since last reply? */ /* Have we sent a heartbeat message asking for reply, since last reply? */
static bool waiting_for_ping_response = false; static bool waiting_for_ping_response = false;
@ -796,6 +797,15 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
logical_read_xlog_page, logical_read_xlog_page,
WalSndPrepareWrite, WalSndWriteData); WalSndPrepareWrite, WalSndWriteData);
/*
* Signal that we don't need the timeout mechanism. We're just
* creating the replication slot and don't yet accept feedback
* messages or send keepalives. As we possibly need to wait for
* further WAL the walsender would otherwise possibly be killed too
* soon.
*/
last_reply_timestamp = 0;
/* build initial snapshot, might take a while */ /* build initial snapshot, might take a while */
DecodingContextFindStartpoint(ctx); DecodingContextFindStartpoint(ctx);
@ -1693,7 +1703,7 @@ WalSndComputeSleeptime(TimestampTz now)
{ {
long sleeptime = 10000; /* 10 s */ long sleeptime = 10000; /* 10 s */
if (wal_sender_timeout > 0) if (wal_sender_timeout > 0 && last_reply_timestamp > 0)
{ {
TimestampTz wakeup_time; TimestampTz wakeup_time;
long sec_to_timeout; long sec_to_timeout;
@ -1735,6 +1745,10 @@ WalSndCheckTimeOut(TimestampTz now)
{ {
TimestampTz timeout; TimestampTz timeout;
/* don't bail out if we're doing something that doesn't require timeouts */
if (last_reply_timestamp <= 0)
return;
timeout = TimestampTzPlusMilliseconds(last_reply_timestamp, timeout = TimestampTzPlusMilliseconds(last_reply_timestamp,
wal_sender_timeout); wal_sender_timeout);
@ -1764,7 +1778,10 @@ WalSndLoop(WalSndSendDataCallback send_data)
initStringInfo(&reply_message); initStringInfo(&reply_message);
initStringInfo(&tmpbuf); initStringInfo(&tmpbuf);
/* Initialize the last reply timestamp */ /*
* Initialize the last reply timestamp. That enables timeout processing
* from hereon.
*/
last_reply_timestamp = GetCurrentTimestamp(); last_reply_timestamp = GetCurrentTimestamp();
waiting_for_ping_response = false; waiting_for_ping_response = false;
@ -2879,7 +2896,11 @@ WalSndKeepaliveIfNecessary(TimestampTz now)
{ {
TimestampTz ping_time; TimestampTz ping_time;
if (wal_sender_timeout <= 0) /*
* Don't send keepalive messages if timeouts are globally disabled or
* we're doing something not partaking in timeouts.
*/
if (wal_sender_timeout <= 0 || last_reply_timestamp <= 0)
return; return;
if (waiting_for_ping_response) if (waiting_for_ping_response)