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[pslawek83 <pslawek83@xxxxx>]

Innodb buffer pool should be probably around 10-20GB if you're going to use just one single innodb table. Currently you are probably killing mariadb with these 1.3k threads. First you can try to limit threads running simultaneusly to 5-30 because you're not goint to have any performance benefit from going above certain (rather low) point, you'll only produce mutex contention so the server will became overloaded with thread coordination code rather than doing any real work. 50 threads would be probably too much already, and you have 20 times that ;)   Not sure if you're doing single op per transaction but without changes to code you probably won't be able to make this app run considerably faster anyway. Because small ops, like couter increment will never be fast in SQL so you'll need some intermediate "aggregation" step to issue as few sql commands and as few transactions as possible.   In your C app you probably need to preprocess and aggregate the data. You take eg. 100k operations and process them in memory. So eg. insert, modify and set on same PK would became just single set. Then you can further divide these 100k operations into 1k-ops transactions.   At the end you can parallelize by starting many instances of the application and spreading the keys over using CRC32. So probably what you'll need to do is:   1. aggregate as many operations as possible  2. divide to N chunks  3. read all affected keys for chunk X in single query  4. modify data in memory  5. output a transaction  6. goto 3 untill all chunks are done   Dnia 7 października 2019 18:17 JCA <1.41421@xxxxxxxxx> napisał(a):  I am running MariaDB 10.0.34 on a Slackware 14.2 system. I have a C application that interacts with MariaDB in the following way:   1. Read data from a FIFO.  2. Insert  the data into a table in a MariaDB database, if absent, or modify it according to certain specific criteria otherwise.   This works as expected.   The problem that I  have is that data are being written to the FIFO at a fast rate. In order to be able to keep up, at any given time my application reads the data available at the FIFO, and spawns a thread to process the chunk of data just read. It is in this thread that all the database interaction takes place.  In order to deal with this, I have the following entries in my /etc/my.cnf file:   # this is read by the standalone daemon and embedded servers  [server]   # this is only for the mysqld standalone daemon  [mysqld]  # thread_handling=pool-of-thread  # log=/var/log/mysqld.log   # this is only for embedded server  [embedded]   # This group is only read by MariaDB servers, not by MySQL.  # If you use the same .cnf file for MySQL and MariaDB,  # you can put MariaDB-only options here  [mariadb]  # log=/var/log/mysqld.log  general_log_file        = /var/lib/mysql/mysql.log  # general_log             = 1   # transaction-isolation = READ-COMMITTED   # key_buffer = 1280M                              # 128MB for every 1GB of RAM   # sort_buffer_size =  1M                          # 1MB for every 1GB of RAM   # read_buffer_size = 1M                           # 1MB for every 1GB of RAM   # read_rnd_buffer_size = 1M                       # 1MB for every 1GB of RAM   # thread_concurrency = 24                         # Based on the number of CPUs                                                     # so make it CPU*2   # thread-handling=pool-of-thread   # innodb_flush_log_at_trx_commit != 1   # open_files_limit = 50000   thread-handling=pool-of-thread   max_connections = 1000  table_open_cache = 800  query_cache_type = 0  innodb_buffer_pool_size = 512M  innodb_buffer_pool_instances = 10  innodb_adaptive_hash_index_par = 20  innodb_lock_wait_timeout = 5000  With this, my application can keep up with the FIFO writer, but - depending on the circumstances - my database can't. As I am writing this, there are over 1300 threads connected to my database; any command that I issue at the mysql CLI takes over one minute to return. I am keeping track on how long each thread takes to complete, and that is of the order of hundreds of seconds - sometimes thousands. Each thread is itself simple, in that it just issues a couple of simple MariaDB commands.  Currently my table consists of 1.6 million entries, and growing - on this basis, I expect that things will get only worse. Each entry,however, will never require more than a couple of hundred bytes of storage. The operations that can be undertaken on entries are insertion, deletion and modification, the latter being straightforward - like e.g. incrementing a counter or replacing a short string.   My system has 24 GB of  RAM and 12 cores. Occasionally all the cores are fully busy with MariaDB activity, but most of the time barely one or two are.   I am a newbie when it comes to interacting with MariaDB - please,  bear with me. I know I must use a single database and a single table. I also know - because of the nature of the data that are being written to the FIFO - that the  probability for two different threads to be operating on the same entry in the table at the same time is negligible - i.e. for all practical purposes, that will not happen.   What I need is advice on how to configure my instance of MariaDB to perform optimally in the scenario above. In particular, I would like for it to make better use of all the cores available - in essence, to parallelize the database operations as much as possible.   Feedback from the experts will be much appreciated.   ______________________________  Mailing list:  launchpad.net launchpad.net  Post to     :   maria-discuss@lists.launchpad.  Unsubscribe :  launchpad.net launchpad.net  More help   :  help.launchpad.net help.launchpad.net