PostgresqlHighRateDeadlock #

Postgres detected deadlocks

alert: PostgresqlHighRateDeadlock
annotations:
  description: |-
    Postgres detected deadlocks
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/postgres-exporter/postgresqlhighratedeadlock/
  summary: Postgresql high rate deadlock (instance {{ $labels.instance }})
expr: increase(postgresql_errors_total{type="deadlock_detected"}[1m]) > 1
for: 0m
labels:
  severity: critical

Here is the runbook for the Prometheus alert rule PostgresqlHighRateDeadlock:

Meaning #

A high rate of deadlocks has been detected in the PostgreSQL database. Deadlocks occur when two or more transactions are blocked, each waiting for the other to release a resource. This can lead to performance issues, errors, and even crashes.

Impact #

• Performance degradation: Deadlocks can cause transactions to stall, leading to increased response times and decreased throughput.
• Errors and failures: Deadlocks can cause transactions to fail, resulting in errors and potential data loss.
• System instability: In severe cases, deadlocks can cause the database to become unresponsive or crash.

Diagnosis #

To diagnose the root cause of the deadlocks, follow these steps:

1. Check the PostgreSQL error logs for deadlock messages.
2. Investigate the transactions involved in the deadlock using the pg_locks and pg_stat_activity views.
3. Analyze the database schema and transaction patterns to identify potential bottlenecks and conflicts.
4. Review the database configuration and tuning parameters, such as max_locks_per_transaction and deadlock_timeout.

Mitigation #

To mitigate the high rate of deadlocks, follow these steps:

1. Immediate mitigation: Restart the PostgreSQL database or roll back transactions to release any held locks.
2. Short-term mitigation: Adjust database configuration and tuning parameters, such as increasing max_locks_per_transaction or decreasing deadlock_timeout, to reduce the likelihood of deadlocks.
3. Long-term mitigation: Implement changes to the database schema and transaction patterns to reduce contention and bottlenecks. This may involve rewriting queries, adding indexes, or modifying the database design.
4. Monitoring and prevention: Implement proactive monitoring and alerting to detect potential deadlocks earlier, and take preventative measures such as restructuring transactions or adding retry mechanisms.

Remember to investigate and address the root cause of the deadlocks to prevent future occurrences.