Classic Server could hung with (near) 100% CPU load ---------------------------------------------------
Key: CORE-4615 URL: http://tracker.firebirdsql.org/browse/CORE-4615 Project: Firebird Core Issue Type: Bug Components: Engine Affects Versions: 2.5.3, 2.5.2 Update 1, 2.5.2 Environment: Classic Server\Super Classic Reporter: Vlad Khorsun There are few reports from few customers that under some (not very well known) conditions Classic Server (or SuperClassic) could stop response. At least one process could use almost 100% of CPU (core). Almost no IO. The issue is very rare, Firebird could work days or weeks without a problem. Memory dump shows very deep recursive calls of CCH\downgrade() function. Sometimes, in SuperClassic we see the cases when another thread runs also very deep calls of CCH\write_buffer() function. It was never reproduced by me, so i don't know exact reason for this issue. There is an idea that while AST thread writes pages and cleans dependencies, worker thread doing some work (garbage collection of a very long versions chain, for example) and re-creates same dependencies, forcing AST thread to clean them again and again. In attempt to fix it we disabled engine checkouts when thread handles AST routine. It makes worker thread to wait while AST is processed. Must note, that before v2.5 engine always works this way. Customers with private build was satisfied and i decided to commit the patch. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://tracker.firebirdsql.org/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel