On Mon, Nov 13, 2006 at 09:23:52PM -0800, John McCullough wrote:
> Hello,
>
> I am working on forking hvm domains and I have been using xenstore to
> send commands to qemu. I have noticed that occasionally qemu's watch is
> not read. I am using the qemu fd handler methods. I have been trying
> to duplicate the missed read outside of qemu and the rest of xend, but I
> haven't been able to. However, I think I may have discovered a memory
> leak in lowlevel/xs/xs.c.
>
> I am attaching:
> - commandee.c : consumer of "commands"
> - commander.py : issuer of commands
> - xsblockingchannel.py : com channel for the commander
>
> I am working against a changset from midsummer (11536:041be3f6b38e)
> since I'm trying to iron out some of my bugs before moving forward in
> the revisions.
>
> % gcc -o commandee commandee.c /usr/lib/libxenstore.a -lpthread
> % sudo ./commandee > /dev/null
> % time sudo python commander.py > /dev/null #(in separate terminal)
> Traceback (most recent call last):
> File "commander.py", line 9, in ?
> xsbc = xsblockingchannel.xsblockingchannel("test")
> File "/net/xen/xsstress/xsblockingchannel.py", line 19, in __init__
> self.xs.watch(self.path, self)
> xen.lowlevel.xs.Error: (12, 'Cannot allocate memory')
> Exception xen.lowlevel.xs.Error: (2, 'No such file or
> directory') in <bound method xsblockingchannel.__del__ of
> <xsblockingchannel.xsblockingchannel instance at 0xb7ce448c>> ignored
>
> 1.02s user 5.00s system 8% cpu 1:08.61 total
I can't remember the details, but I have vague recollection of a
Xenstore-related problem where the error was ENOMEM, but that error was
misleading.
One thing you can try is to run xenstore in trace mode: export
XENSTORED_TRACE=1 before running xend, which will add "-T
/var/log/xen/xenstored-trace.log" to the xenstore command line. This will
give you a log of every operation on the store, which will tell us whether the
error code is coming from xenstore.
Regarding the missing read -- that's probably because you are not handling
EAGAIN when doing xs_transaction_end. You need to retry if xs_transaction_end
fails with errno = EAGAIN, being careful not to allocate memory each retry.
See xenstore_client.c for example.
Ewan.
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home