… (like allocator from glibc) this will notably slowdown MySQL-transaction creation and many threads will get stuck on glibc/kernel syscalls, which… can be the reason for notable MySQL performance drop. Now in Percona Server, for each connection we use a preallocated read view structure, reuse that memory during the entire connection lifetime and free it at disconnect. If some transactions require…
Post: Memory allocators: MySQL performance improvements in Percona Server 5.5.30-30.2
April 15, 2013 By
Post: trx descriptors: MySQL performance improvements in Percona Server 5.5.30-30.2
April 12, 2013 By 3 Comments
… reported as a part of MySQL bug #49169 and can be described as follows. Whenever a connection wants to create a consistent…. there’s a notable drop in throughput starting from 256 threads. But Percona Server’s scalability is the same as in… scan and it provides stable throughput even at 4096 concurrent connections. So both the general “trx descriptors” optimization introduced in Percona…
Post: High-load problems? Investigate them with 'pt-query-digest'
April 23, 2013 By 2 Comments
… up pt-stalk to trigger a capture if Threads_running went above a known ‘good’ value for…to review them in servers with thousands of connections. Enter pt-query-digest. The tool supports its… you regularly work with MySQL databases, getting familiar with Percona Toolkit for MySQL will let you do more …
Post: Virident vCache vs. FlashCache: Part 2
May 17, 2013 By 3 Comments
…time=7200 –max-requests=0 –percentile=95 \ –mysql-user=root –mysql-socket=/tmp/mysql.sock –mysql-table-engine=innodb \ –oltp-read-only=off …innodb_purge_threads = 1 innodb_fast_shutdown = 1 #not innodb options (fixed) back_log = 50 wait_timeout = 120 max_connections = 5000 max…
Post: Benchmarking Percona Server TokuDB vs InnoDB
May 7, 2013 By 32 Comments
…=32 –mysql_table_engine=tokudb –oltp_auto_inc=on –max-time=18000 –report-interval=10 –max-requests=0 –num-threads=32 –rand…_threads = 4 innodb_io_capacity = 4000 innodb_use_native_aio=0 #not innodb options (fixed) port = 3306 back_log = 50 max_connections…_extra_sort_file_size = 10G myisam_repair_threads = 1 myisam_recover socket=/var/lib/mysql/mysql.sock user=root skip-grant-tables TokuDB…
Post: MySQL Limitations Part 4: One thread per connection
October 27, 2010 By 14 Comments
… limiting MySQL in core use cases (links: part 1, 2, 3). This post is about the way MySQL handles connections, allocating one thread per connection to the server. MySQL is a single process with multiple threads. Not all databases…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…MySQL…commanual connect_…thread_cache_sizeblogpercona.commanual thread_concurrencyblogpercona.commanual thread_handlingblogpercona.commanual thread_stackblogpercona.commanual Threads_cachedblogpercona.commanual Threads_connectedblogpercona.commanual Threads_createdblogpercona.commanual Threads…
Post: MySQL Connection Timeouts
April 19, 2011 By 4 Comments
… look into how MySQL accepts connection. There is single main thread which is accepting connections coming to LISTEN sockets. Once there is connection coming it… connection and create a new thread or take one out of the thread cache. From this point on MySQL processes network communication in multiple threads…
Post: How Percona diagnoses MySQL server stalls
March 3, 2011 By 6 Comments
… I work on show up as abnormally high values of Threads_connected or Threads_running. That’s a good place to start for… check for. VARIABLE=${VARIABLE:-Threads_connected} You need to change the threshold to 15, and the variable to Threads_running. Check the other…. There are many things that can cause a stall in MySQL, and they usually begin microscopically and get worse over time…
Post: How to debug long-running transactions in MySQL
March 8, 2011 By 6 Comments
…-plugin InnoDB versions, you can’t reliably figure out what connection is to blame for blocking others. You can guess, and…_id INNER JOIN information_schema.processlist p on b.trx_mysql_thread_id = p.ID LIMIT 1′) if [ "${host}" ]; then echo “Host… iterations. And watch your server to find idle-in-transaction connections that are just sitting there doing nothing, and kill them…
