Release notes for Patch #1841

  • Very often, especially under high loads, the virtual memory occupation for the glite-wms-workload_manager process may reach very high values, such as one Gigabyte and more. Despite what one might think at first sight, this is not about a memory leak, but simply the effect of the so called per-thread arenas. The WM in fact, keeps in memory requests and a very large data structure containing up-to-date resource information, the so called information supermarket, which is accessed by several threads. With the linux standard malloc implementation (ptmalloc2) all this data cause the memory to grow large. See tcmalloc for a detailed explanation. Especially wherever RAM is less than or equal to 4Gb, it is highly suggested to workaround this problem using run-time redirection to whatever lock-free, optimized alternative allocator, to avoid excessive swap activity. Here is our recipe which makes use of the TCmalloc, such an alternate allocator distributed by Google under BSD license:
    • after installing the two rpms, google-perftools-devel-???.rpm and google-perftools-???.rpm (whichever version should be fine),
    • you can use tcmalloc this way: export LD_PRELOAD="/usr/lib/" in the glite-wms-wm script. Even if not specifically recommended (actually it may not work with everything) run-time malloc redirection has proven to get well along with the glite workload manager, so that it can be used without any problem in such circumstances.

-- AlessioGianelle - 27 May 2008

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Topic revision: r1 - 2008-05-27 - AlessioGianelle
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