View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000020 | Pgpool-II | Bug | public | 2012-08-01 01:00 | 2012-11-26 16:00 |
| Reporter | singh.gurjeet | Assigned To | t-ishii | ||
| Priority | high | Severity | major | Reproducibility | always |
| Status | resolved | Resolution | reopened | ||
| Platform | Linux 64bit | OS | Ubuntu | OS Version | 12.04 |
| Summary | 0000020: pgpool does not accept connections after postgres hits the max_connections limit | ||||
| Description | I have reported this bug to -hackers list [1], Repeating it here for the follow-up. As per the docs: - *Limiting Exceeding Connections* There is a limit on the maximum number of concurrent connections with PostgreSQL, and connections are rejected after this many connections. Setting the maximum number of connections, however, increases resource consumption and affect system performance. pgpool-II also has a limit on the maximum number of connections, but *extra connections will be queued instead of returning an error immediately.* So one would expect the application to wait indefinitely if the connection parameter pair (user, database) that it is requesting is not yet available, but I see that the application connections are terminated immediately. Given that pgpool advertises that 'extra connections will be queued instead of returning an error immediately", I think we should treat this as a bug, unless there's something wrong with my configuration. [1] http://www.sraoss.jp/pipermail/pgpool-hackers/2012-August/000102.html | ||||
| Steps To Reproduce | Here's how I tested this on version 3.1.3 and master branch ( 3.2.0 RC3, commit id: 1c584a84). .) Start a single Postgres database instance (version PostgreSQL 9.1.4) .) Create 2 databases : test and test2 .) Start pgpool as follows: (config files attached) inst/bin/pgpool -f ~/Downloads/pgpool.conf -F ~/Downloads/pcp.conf -a ~/Downloads/pool_hba.conf .) In one terminal, run psql clients, one at a time, to connect to 'test' database, over pgpool: export PGHOST=localhost PGPORT=9999 PGDATABASE=test PGUSER=postgres while sleep 1; do psql -c "select datname, now()::timestamp(0), count(*) from pg_stat_activity group by datname"; done .) In other terminal, run psql clients, one at a time,, to connect to 'test2' database over pgpool: export PGHOST=localhost PGPORT=9999 PGDATABASE=test2 PGUSER=postgres while sleep 1; do psql -c "select datname, now()::timestamp(0), count(*) from pg_stat_activity group by datname"; done After a few seconds, in the second terminal, when the total connections on Postgres server have all been exhausted, I see the psql connections failing: datname | now | count ---------+---------------------+------- test | 2012-07-31 11:17:49 | 75 test2 | 2012-07-31 11:17:49 | 25 (2 rows) psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: psql: ^C gurjeet at work:~/dev/POSTGRES T111809 (pg_9.1_stable)$ | ||||
| Tags | No tags attached. | ||||
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Did you follow the guide in the doc? In summary, max_pool, num_init_children, max_connections, superuser_reserved_connections must satisfy the following formula: max_pool*num_init_children <= (max_connections - superuser_reserved_connections) (no query canceling needed) max_pool*num_init_children*2 >= (max_connections - superuser_reserved_connections) (query canceling needed) |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2012-08-01 01:00 | singh.gurjeet | New Issue | |
| 2012-08-01 01:00 | singh.gurjeet | File Added: pgpool_bug_report.tgz | |
| 2012-08-17 08:12 | t-ishii | Note Added: 0000044 | |
| 2012-08-17 08:17 | t-ishii | Status | new => resolved |
| 2012-11-26 16:00 | t-ishii | Assigned To | => t-ishii |
| 2012-11-26 16:00 | t-ishii | Status | resolved => feedback |
| 2012-11-26 16:00 | t-ishii | Resolution | open => reopened |
| 2012-11-26 16:00 | t-ishii | Status | feedback => resolved |
