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Fix PS connect attempt timeouts when facing interrupts (#11880)

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With the 50ms timeouts of pumping state in connector.c, we need to
correctly handle these timeouts that also wake up pg_usleep.

This new approach makes the connection attempts re-start the wait
whenever it gets woken up early; and CHECK_FOR_INTERRUPTS() is called to
make sure we don't miss query cancellations.

## Problem

https://neondb.slack.com/archives/C04DGM6SMTM/p1746794528680269

## Summary of changes

Make sure we start sleeping again if pg_usleep got woken up ahead of
time.
This commit is contained in:
Matthias van de Meent
2025-05-09 19:02:24 +02:00
committed by GitHub
parent 33abfc2b74
commit 3b7cc4234c
1 changed files with 10 additions and 2 deletions
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12
pgxn/neon/libpagestore.c
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@@ -433,7 +433,6 @@ pageserver_connect(shardno_t shard_no, int elevel)
now = GetCurrentTimestamp();
us_since_last_attempt = (int64) (now - shard->last_reconnect_time);
shard->last_reconnect_time = now;
/*
* Make sure we don't do exponential backoff with a constant multiplier
@@ -447,14 +446,23 @@ pageserver_connect(shardno_t shard_no, int elevel)
/*
* If we did other tasks between reconnect attempts, then we won't
* need to wait as long as a full delay.
*
* This is a loop to protect against interrupted sleeps.
*/
if (us_since_last_attempt < shard->delay_us)
while (us_since_last_attempt < shard->delay_us)
{
pg_usleep(shard->delay_us - us_since_last_attempt);
/* At least we should handle cancellations here */
CHECK_FOR_INTERRUPTS();
now = GetCurrentTimestamp();
us_since_last_attempt = (int64) (now - shard->last_reconnect_time);
}
/* update the delay metric */
shard->delay_us = Min(shard->delay_us * 2, MAX_RECONNECT_INTERVAL_USEC);
shard->last_reconnect_time = now;
/*
* Connect using the connection string we got from the