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When the storage of a guest hosted on a Red Hat Virtualization Hypervisor system became inaccessible, the host in some cases became unresponsive. This update fixes the behavior of the virDomainMemoryStats() function, which prevents the described problem from occurring.
Verified on libvirt-python-3.2.0-3.el7_4.1
Reproduce steps on libvirt-python-3.2.0-3.el7:
1. prepare nfs with iso in it and add this cdrom in guest xml
2. restart libvirtd
3. on console 1, run
# python ./test.py
We can see the output for main thread and other 2 threads, and the vm started
run abount 30-40s, on console 2 run
# iptables -A OUTPUT -d [NFS_SERVER] -j DROP
to block the nfs access
For several min, the qemu process into Dl state, and the output for print will hang for 30s, see the time I marked in the log
*******
print time: 2017-10-09 19:44:06.384147
print time: 2017-10-09 19:44:07.385305
print time: 2017-10-09 19:44:08.386450
start memoryStats: 2017-10-09 19:44:08.395628 <------------- here the time
libvirt: QEMU Driver error : Timed out during operation: cannot acquire state change lock (held by remoteDispatchConnectGetAllDomainStats)
print time: 2017-10-09 19:44:38.395709
Exception in thread Thread-2:
Traceback (most recent call last):
File "/usr/lib64/python2.7/threading.py", line 812, in __bootstrap_inner
self.run()
File "/usr/lib64/python2.7/threading.py", line 765, in run
self.__target(*self.__args, **self.__kwargs)
File "./test.py", line 19, in memory_stats
dom.memoryStats()
File "/usr/lib64/python2.7/site-packages/libvirt.py", line 1450, in memoryStats
if ret is None: raise libvirtError ('virDomainMemoryStats() failed', dom=self)
libvirtError: Timed out during operation: cannot acquire state change lock (held by remoteDispatchConnectGetAllDomainStats)
print time: 2017-10-09 19:44:39.396900 <-------------- here the time
print time: 2017-10-09 19:44:40.398037
print time: 2017-10-09 19:44:41.399191
**********
On libvirt-python-3.2.0-3.el7_4.1 the print will finished without hang, so verify it.
The test xml and scripts will be given on attachment
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2017:2948