[OpenAFS-devel] client-idledeadtime-support-20080430 causes connection time outs

[Jeffrey Altman]

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On 9/4/2009 5:53 AM, Rainer Toebbicke wrote:
> I believe client-idledeadtime-support-20080430 is a bit unfair, at leas=
t
> it introduced the following problem, possibly on a wrong assumption:
>=20
> time 502.579567, pid 2195: Analyze RPC op 6 conn 0x4ae0b240 code
> 0xfffffffd user 0x0
> time 502.579581, pid 2195: afs_Analyze out shouldRetry 0
> time 502.579608, pid 2195: Returning code -3 from 21
>=20
> in words: an RXAFS_RemoveFile received an RX_CALL_TIMEOUT (-3), there i=
s
> no alternative server, and hence the operation is not retried. It would=

> have been retried in the RX_CALL_DEAD (-1) case (and plenty of other
> cases).
>=20
> The comment in the code justifies that special treatment for
> RX_CALL_TIMEOUT on the grounds that the call has timed out while server=

> was still responding to other calls. From the RX code I fail to see how=

> this is necessarily correct: rxi_CheckCall can be called from the
> keepalive mechanism and stop the call without any interaction from the
> server, you can get RX_CALL_TIMEOUT and not e.g. RX_CALL_DEAD even if
> the server is completely hosed.
>=20
> In this particular case the server was stopped, the "hard mount"
> functionality should have ensured that I/Os stay pending until the
> server was restarted.
>=20
> Now, I don't know how to solve the yoyo up-down-up problem in case a
> server times out calls selectively. When it happens, for
> single-server-volumes the call should be retried in most cases.
>=20
> Would it be reasonable to blacklist only up to the last server and then=

> go the usual path which ensures a fair retry?
>=20
> (Actually, I wonder whether you can ensure you never get RX_CALL_TIMEOU=
T
> if a server is simply restarted, which certainly deserves a retry).

There was a bug in the idle dead timeout processing in the rx library.
A timeout would occur if the send window was full for longer than the
timeout period.  This is fixed by

  http://gerrit.openafs.org/#change,1183

Jeffrey Altman


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