Red Hat Bugzilla – Bug 210141
XenD HTTP service serializes all requests
Last modified: 2007-11-30 17:07:35 EST
Description of problem: Libvirt talks to XenD over its HTTP service. Unfortunately the HTTP service implementation is single-threaded, so all incoming requests are serialized. This may not sound so bad until you consider that the 'VM Create' operation can take anywhere from 5- 60 seconds to complete. During this time no other requests to XenD will even be started. This means that *all* other applications using libvirt will be blocked / hang until the create operation completes. Version-Release number of selected component (if applicable): xen-3.0.2-44 How reproducible: Frequently Steps to Reproduce: 1. Make a long running request to XenD (eg, a VM Create operation) 2. Attempt to make another unrelated request (eg list domains) at the same time 3. Actual results: The list domains request isn't processed until the create operation finishes Expected results: The requests are processed in parallel Additional info: I posted a prototype patch upstream to make XenD multi-threaded http://lists.xensource.com/archives/html/xen-devel/2006-10/msg00264.html
We'd like this as a Beta2 blocker, but this isn't required.
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux release. Product Management has requested further review of this request by Red Hat Engineering. This request is not yet committed for inclusion in release.
It has been posted upstream twice now, but no feedback has been forthcoming yet. http://lists.xensource.com/archives/html/xen-devel/2006-10/msg01176.html
Merged upstream in 12776:c287052a0a654a74153f176fbd8159cb1d75211b http://xenbits.xensource.com/xen-unstable.hg?rev/c287052a0a65
This is built into xen-3.0.3-29.el5 in dist-5E-qu-candidate. To test try the following: 1. Create a guest VM with 1 GB of RAM 2. Crete a second guest VM 'B' 3. Open two console windows 4. In one run 'virsh save [guest A] /var/lib/xen/test.save 5. At the same time as this is running, also run 'virsh dumpxml [guest B]' many times over. Prior to thsi fix, step 4 would 'hang' until step 3 completed. With this fix, you should be able to run step 4 without seeing any hang.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHEA-2007-0635.html