…. Now, Valgrind does not need much introduction, especially to the MySQL server developers. The Valgrind Memcheck tool, which is synonymous with… 800000 alloc’d ==9090== at 0x4C28FDF: malloc (vg_replace_malloc.c:236) ==9090== by 0x6BE309B: ut_malloc (ut0mem.c:106) ==9090== by 0x6BC8074…
Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
I am constantly referring to the amazing MySQL manual, especially the option and variable reference table. But just …
Post: InnoDB memory allocation, ulimit, and OpenSUSE
August 23, 2010 By 7 Comments
… error message was an assert due to a failed malloc() in ut_malloc_low() in ut/ut0mem.c inside InnoDB source code. InnoDB wraps the majority of its memory allocations in ut_malloc_low(), so to get an idea of the pattern of… GB from one. In fact, 80GB allocation failed right in malloc(), did not even get to initialization. I tested it with…
Post: Read Buffers, mmap, malloc and MySQL Performance
September 12, 2007 By 8 Comments
… – o_profile (often together with strace) are great tools for MySQL Performance analyses. Too many people end tuning on plans and… speed things up here ? Of course you can tune you malloc settings so more buffers are allocated from the pools rather…’m not sure how much luck you will have with malloc algorithms if they are forced to deal with very large…
Post: MySQL, AIX5L and malloc()
November 3, 2008 By 11 Comments
… I conceived the idea to use one spare partition for MySQL tests. Because I had no past experience with it and… from the beginning.. For any reason, you decided to run MySQL database on AIX 5L operating system. You compiled it successfully… N is the number of segments. So, to make your MySQL working fine: export LDR_CNTRL=’MAXDATA=0×80000000′ It…
Post: How is join_buffer_size allocated?
July 5, 2010 By 9 Comments
When examining MySQL configuration, we quite often want to know how various buffer …_buff_size, cache->length); 14272 if (!(cache->buff=(uchar*) my_malloc(size,MYF(0)))) 14273 DBUG_RETURN(1); /* Don’t use… bad happens, you might be seeing this bug: http://bugs.mysql.com/55002
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
…_pool_size is just a handy way to avoid repeated malloc() calls by doing it all up front in one call…_allowed_packet bigger and ran the following on my laptop: mysql> set @a := repeat(‘a’, 1024 * 1024 * 100); Query OK, 0 rows affected (2.34 sec) mysql> select get_lock(@a, 1); +—————–+ | get_lock(@a, 1) | +—————–+ | 1…
Comment: To UUID or not to UUID ?
March 14, 2007 By 28 Comments
…/ It also seems that the poor performance of glibc’s malloc has been previously documented: http://www.mail-archive.com/openldap… there seems to be a few alternatives out there replace malloc: http://www.cs.umass.edu/~emery/hoard/hoard-documentation.html… a good idea to replace malloc with one of the above solutions if you’re using MySQL in a 4+ cores system…
Comment: To UUID or not to UUID ?
March 15, 2007 By 28 Comments
… tweakers benchmarks there are new one with “fixed” MySQL version. But even “fixed” mysql is far from scaling perfectly. I have not… on the Malloc tests. It is interesting it changes well with Google Malloc as in fact we’ve benchmarked number of malloc alternatives including hoard.org and bumch of alternative ones with no serious effect. This was not surprising especially as MySQL…
Comment: InnoDB memory allocation, ulimit, and OpenSUSE
August 31, 2010 By 7 Comments
…: Thanks for the clarifications. Good to know. Dimitri: This was MySQL Percona version 5.0.91. However, the issue of needing… InnoDB or plain crashing because that is a dangerous game. malloc() can return successfully, but it does not mean that all… to segfault while writing to a successfully allocated block that malloc() returned! However, if we tried to explain where the memory…
