class Deimos::Utils::DeadlockRetry
Utility class to retry a given block if a a deadlock is encountered. Supports Postgres and MySQL deadlocks and lock wait timeouts.
Constants
- DEADLOCK_MESSAGES
Need to match on error messages to support older Rails versions
- RETRY_COUNT
Maximum number of times to retry the block after encountering a deadlock
Public Class Methods
Retry the given block when encountering a deadlock. For any other exceptions, they are reraised. This is used to handle cases where the database may be busy but the transaction would succeed if retried later. Note that your block should be idempotent and it will be wrapped in a transaction. Sleeps for a random number of seconds to prevent multiple transactions from retrying at the same time. @param tags [Array] Tags to attach when logging and reporting metrics. @yield Yields to the block that may deadlock.
# File lib/deimos/utils/deadlock_retry.rb, line 31 def wrap(tags=[]) count = RETRY_COUNT begin ActiveRecord::Base.transaction do yield end rescue ActiveRecord::StatementInvalid => e # Reraise if not a known deadlock raise if DEADLOCK_MESSAGES.none? { |m| e.message.include?(m) } # Reraise if all retries exhausted raise if count <= 0 Deimos.config.logger.warn( message: 'Deadlock encountered when trying to execute query. '\ "Retrying. #{count} attempt(s) remaining", tags: tags ) Deimos.config.metrics&.increment( 'deadlock', tags: tags ) count -= 1 # Sleep for a random amount so that if there are multiple # transactions deadlocking, they don't all retry at the same time sleep(Random.rand(5.0) + 0.5) retry end end