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[Xen-users] Re: [Xen-API] Frequent I/O error of HTTP server and memory e

To: Dave Scott <Dave.Scott@xxxxxxxxxxxxx>
Subject: [Xen-users] Re: [Xen-API] Frequent I/O error of HTTP server and memory error on XenServer5.6 FP1
From: Frank <frank@xxxxxxxxx>
Date: Thu, 13 Jan 2011 14:54:21 -0800
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Thank you. Are there many changes from 5.6 to 5.6FP1? with same software, xenserver5.6 works fine. anyway, I will try your method to see how many threads run when the problem happens

On 01/13/2011 02:41 PM, Dave Scott wrote:

My best guess is that the "Thread.create: Cannot allocate memory" means that 
there's insufficient virtual address space in the process to allocate a 10MiB thread 
stack. I suspect this is being caused by there being too many threads (approx 300 is the 

Since xapi currently uses a thread per connection model there are probably too 
many open connections -- could you describe the software which is using the 
apache xmlrpc client? Is it possible that someone is opening connections but 
not closing them quickly enough?

If you install gdb and attach it to the running (child -- the big one) xapi 
process it'll tell you how many threads are present and allow you to examine 
the stacks of each one ('thread apply all bt') -- it should be easy to spot 
where the threads are blocked (e.g. in a network recv or perhaps on a 

At some point in future we'll have to switch to a different threading model and 
make the connection handling more robust. In the meantime we have to be a bit 
careful about connection cleanup :/


-----Original Message-----
From: xen-api-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-api-
bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Frank
Sent: 13 January 2011 22:14
To: xen-api@xxxxxxxxxxxxxxxxxxx; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-API] Frequent I/O error of HTTP server and memory error
on XenServer5.6 FP1

      I am using XenServer5.6 FP1 GA release with openvswitch as network
backend. When I create VM through xapi,  "apache.xmlrpc.XmlRpcException:
I/O error" happens very frequently. At meanwhile my xencenter lost
connection to hosts.
      Another thing is when I tried to kill VMs from xencenter, it
complains "Internal error:Sys_error("Thread.create: Cannot allocate
memory")", see attached picture.
      does anyone meet similar errors?
      Thank you.

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