Release notes for Patch #1841

New release (08_98) of the WMS for gLite3.1/SL4. Changes with respect to the current production version:

  • 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.

  • LDAP queries used to fetch information in the Information Supermarket from the BDII can now be pre-filtered. This is very helpful whenever a WMS instance is dedicated to only one VO. Typically, using a production BDII, the ISM reaches a size of 6-7000 entries, with the consequence that the match-making time for a job can take up to ten seconds. Using the filter on the VO name, as for the mentioned use-case, significantly reduces the times for MM. The filter expression is specified using an environment variable, as shown in this example:

  • Temporarily removed the purchasing from CEMon.

  • Added the possibility to submit to a CREAM-CE through a new component called ICE

  • DNS load balancing

  • JobDir as input mechanism to WM in place of FileList. Tool available for conversion. Should it be done automatically? Or would it be better to put the WMS in drain during the transition?

  • Add recovery procedure for the WM (EnableRecovery = true). Notice: if the recovery is not enabled, starting and stopping the workload_manager might cause duplicating requests.

  • No more support for RGMA as information system.

  • Deprecated components:
    • checkpointing (glite-wms-checkpointing)
    • partitioner (glite-wms-partitioner)
    • interactive (glite-wms-interactive and glite-wms-thirdparty-bypass), suggest to use i2glogin with appropriate links
    • rgma (info system)

-- AlessioGianelle - 27 May 2008

This topic: EgeeJra1It > WebHome > ReleaseNotes1841
Topic revision: r10 - 2008-07-29 - MarcoCecchi
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