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Release notes for Patch #1841

Release 08_98 of the WMS for gLite3.1/SL4. Changes with respect to the current production version (patch #1726):

  • Enabled submission to CREAM CE. A newly introduced component in the WMS internal architecture, called ICE, implements the job submission service to CREAM. Its functionality can be compared to what the three components JC. LM and CondorG do for the submission to LCG CE

Important: 1) if the recovery is not enabled, simply starting and stopping the glite-wms-workload_manager process (and of course restarting after whatever kind of interruption) might cause duplicating requests. 2) the recovery only works with "JobDir" (see below)

  • "JobDir" is a mailbox-based persistent communication mechanism, for the moment adopted between the WM proxy and the WM. In the present release it is enabled by default. A tool is available for converting from the former mechanism based on filelist (conversion in the opposite way is also supported). At the moment this not done automatically. Of course, another option to handle this transition will consist in putting the WMS in drain and wait for the filelist to be empty.

  • Modified design to allow for DNS-based load balancing mechanisms

  • LDAP queries to fetch information in the Information Supermarket from the BDII can now be pre-filtered. This can be 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 for a job can take a time of the order of ten seconds. Using the filter on the VO name, as for the aforementioned use-case, significantly reduces the MM time. The filtering expression has to be set by assigning the relevant parameter within the WorkloadManager section of the configuration file, as shown in the following example:
    • IsmIiLDAPCEFilterExt="(|(GlueCEAccessControlBaseRule=VO:cms)(GlueCEAccessControlBaseRule=VOMS:/cms/*))"

  • Purchasing from CEMon has been temporarily disabled

  • Purchasing from R-GMA has been dismissed

  • Added support for MPI jobs according to the latest specifications from the MPI working group. The value "MPICH" for the JDL attribute JobType becomes deprecated from now on, just set it to "Normal" and follow the new guideline instead

  • Support for interactive jobs has been dismissed. However, the functionality is not compromised because it can be achieved using a tool called i2glogin (formerly known as glogin). This different approach is actually more flexible, the user being totally in charge, and it follows the trend set by the new handling for MPI jobs).

  • Known issues:
    • 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. This is not about a memory leak, but simply the effect of a well-known problem with the allocator which comes with the glibc (the so called ptmalloc2). See tcmalloc for a more detailed explanation. This problem can be avoided using run-time redirection to whatever lock-free, optimized alternative allocator, to avoid excessive swap activity. It is highly suggested doing so wherever RAM is less than or equal to 4Gb. Here is our recipe which makes use of the TCmalloc, such an alternate allocator distributed by Google under BSD license:
      • install the two rpms, google-perftools-devel-???.rpm and google-perftools-???.rpm (just pick up the latest version, older versions should work anyway, just in case),
      • enable the malloc redirection for the WM by editing the glite-wms-wm script. It is just a matter of removing the comment in the following line:
    • Bug #40951: Cleared event is not logged for nodes

-- AlessioGianelle - 27 May 2008

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Topic revision: r16 - 2008-09-02 - AlessioGianelle
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