![]() time from the lease, and will tend to reset items before the lease continue to use REQUEST_TIME instead of the current time(), we steal claimed by a single consumer which runs longer than 1 second. We cannot rely on REQUEST_TIME because items might be Only one thread can succeed in UPDATEing the htdocs/includes/bootstrap.inc).ĭrush command terminated abnormally due to an unrecoverable error. Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute.: SELECT 1 FROM WHERE ip = :ip Array PDOException: SQLSTATE: General error: 2014 Cannot execute queries while other unbuffered queries are active. Setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute.: SELECT 1 Alternatively, if your code is onlyĮver going to run against mysql, you may enable query buffering by WD php: PDOException: SQLSTATE: General error: 2014 Cannot Įxecute queries while other unbuffered queries are active. Bonus points is that cache_set is now faster than cache_get. By setting the deadlock timeout to 2 seconds instead of the default of 50 the huge slowdown caused by record locks can be avoided. Writes to the same cid by different processes causes a record lock. Use asynchronous MySQLi connection to avoid RECORD LOCKS (Deadlocks) on cache tables TRUNCATE is a DDL statement and thus locks the table. Waiting for table metadata lock on cache_field table Splitting this up has already been fixed and changing this in D7 would be very hard to support so for now here is a D7 patch that puts locks around changes in order to prevent transactional rollbacks when they conflict. Thinking about this and it seems like the cache_field table needs to be split up into 2 different caches, call one cache_field which stores entity field data and another called cache_field_info for storing cached info about fields. īelow is the SQL to switch this over to a memory table and change the primary key to be name, value instead of name & add a unique index on name.ĪLTER TABLE semaphore ADD PRIMARY KEY (name, value) USING BTREE ĪLTER TABLE semaphore ADD UNIQUE name (name) USING BTREE ĪLTER TABLE semaphore ADD INDEX value (value) USING BTREE ĪLTER TABLE semaphore ADD INDEX expire (expire) USING BTREE ![]() I want to use a BTREE index for memory tables due to this issue. Use READ COMMITTED for MySQL transactionsĬode to add to settings.php for current installs: īelow are patches that are mainly helpful if you are using the database for the cache backend.ĭo not use InnoDB for the semaphore table, use Memoryĭue to limitations with core's database api creating a patch to fix this looks difficult to do. Also noted that this would only be useful on MySQL boxes that have the Improved MEMORY Storage Engine patch and if the the data column has been moved to be the last column due to Memory not supporting BLOB/TEXT column types thus the recommendations below do not use the memory engine for cache tables. Noted that converting some cache tables to memory would only be useful for tables that don't get written to very often & low concurrently due to table level locking. Not everyone can use an alternative cache backend thus getting the best performance out of MySQL is desired. ![]() This is what I've come up with after helping out here. ![]() I've been working on eliminating deadlocks and speeding up the database layer of Drupal. ![]()
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