Hello

I have a report of critical bug (database is temporary unavailability ..
restart is necessary).


A customer use:

PostgreSQL 9.2.4,
24 CPU
140G RAM
SSD disc for all


Database is under high load. There is a few databases with very high number
of similar simple statements. When application produce higher load, then
number of active connection is increased to 300-600 about.

In some moment starts described event - there is a minimal IO, all CPU are
on 100%.

Perf result shows:


           354246.00 93.0% s_lock
/usr/lib/postgresql/9.2/bin/postgres
            10503.00  2.8% LWLockRelease
 /usr/lib/postgresql/9.2/bin/postgres
             8802.00  2.3% LWLockAcquire
 /usr/lib/postgresql/9.2/bin/postgres
              828.00  0.2% _raw_spin_lock
[kernel.kallsyms]
              559.00  0.1% _raw_spin_lock_irqsave
[kernel.kallsyms]
              340.00  0.1% switch_mm
 [kernel.kallsyms]
              305.00  0.1% poll_schedule_timeout
 [kernel.kallsyms]
              274.00  0.1% native_write_msr_safe
 [kernel.kallsyms]
              257.00  0.1% _raw_spin_lock_irq
[kernel.kallsyms]
              238.00  0.1% apic_timer_interrupt
[kernel.kallsyms]
              236.00  0.1% __schedule
[kernel.kallsyms]
              213.00  0.1% HeapTupleSatisfiesMVCC

We try to limit a connection to 300, but I am not sure if this issue is not
related to some Postgres bug.

Regards

Pavel

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