David Lloyd [
http://community.jboss.org/people/dmlloyd] created the discussion
"Re: remote tx inflow: timeouts"
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http://community.jboss.org/message/630267#630267
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Tom Jenkinson wrote:
I don't think I am explaining this well enough.
Say there is a root TM and a subordinate TM with a timeout of say 2 second
time T+0: root TM starts transaction timeout of 2
time T+1: tx flows to subordinate TM (using the remaining amount of timeout at root TM
as the timeout for subordinate TM, i.e. the timeout value appears to be 1 at the
subordinate TM)
time T+2: subordinate TM timesout and forgets about the transaciton AND root TM timesout.
The root TM timeout cascades the abort to all XAResources (remember in the model we are
going for subordinate transaction managers are registered as XAResources so each
subordinate gets a call to abort from the root tm)
time T+3: the subordinate transaction manager receives the abort message from the root TM
via the proxy XAResource but by now has cleaned up the transaction so will return an error
indicating that it can't find the transaction
Yeah I get the potential issue.
The extra time added has to be greater than the expected latency between the time the root
controller issues the timeout notice and the time that the subordinate can receive and
process it.
That said, we need some level of tolerance for the case where the given extra time is not
sufficient and the subordinate node is unable to abort the transaction because it's
already gone, because it +will+ happen at some point. Ideally, this transaction abort
would be idempotent.
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