Bug 733319

Summary: Weird xen not-so-uuids cause libvirtd to delay new connections
Product: [Community] Virtualization Tools Reporter: asuffield
Component: libvirtAssignee: Libvirt Maintainers <libvirt-maint>
Status: CLOSED DEFERRED QA Contact:
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Priority: unspecified    
Version: unspecifiedCC: crobinso, xen-maint
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Last Closed: 2016-03-23 13:38:42 UTC Type: ---
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Description asuffield 2011-08-25 13:15:11 UTC 
This is with libvirt 0.9.0..4 and xen 4.1.0..1 at least.

Observe:
asuffield@dock:~$ sudo xenstore-read /local/domain/1/vm
/vm/3f0bbb2b-3ae8-7bfc-53cf-e22ac61d717b
asuffield@dock:~$ sudo xenstore-read /local/domain/2/vm
/vm/b89bd689-80ae-9b05-4b0e-d156889c39c8
asuffield@dock:~$ sudo xenstore-read /local/domain/0/vm
/vm/00000000-0000-0000-0000-000000000000-24

That last one isn't even close to a valid UUID, not least because it is 34 bytes long. This makes xenStoreDomainIntroduced unhappy here:

            if (xenStoreDomainGetUUID(conn, new_domids[i], uuid) < 0) {
                missing = 1;
                VIR_FREE(name);
                continue;
            }

It will always consider domain 0 to be "missing", so will always delay for 2 seconds of retries.

Xen's silly data should be tolerated or ignored, not cause a retry loop.
Comment 1 Cole Robinson 2016-03-23 13:38:42 UTC 
Sorry this never received a response. You're right that bogus xen data shouldn't cause us issues here, but given that the xend/xenstore libvirt bits aren't as commonly used these days (over libxl), and I suspect xen eventually fixed their side, I doubt this will be fixed in libvirt unless someone sends a patch.

If anyone is still hitting this issue with recent libvirt, please reopen this bug and I can ping one of the xen devs. Until then closing as DEFERRED