I think my try/catch is missing a catch at the end:
catch (final Throwable ex) {
exception = ex;
break; // fail
}
Rusty Wright wrote:
> Ah, thanks. So if I knew how many servers my cloud is made of then I
> should use that number for my MAX_RETRIES. ;-)
>
> I'm curious about how others are handling the exceptions. The
> JDOCanRetryException is subclassed by other exceptions that don't seem
> like things I'd want to retry, but perhaps I don't understand the
> subtleties. Here's what I'm doing; it's an AOP gizmo, courtesy of
> Spring. The pjp.proceed() is where my transaction wrapped method is
> called. Looks clunky to me, given that it's not readily apparent why
> it's doing what it does.
>
> public Object retry(final ProceedingJoinPoint pjp) throws Throwable {
> this.log.debug("called");
>
> JDOException exception = new JDOException("oops; too many retries");
>
> int retryCount = 0;
>
> while (retryCount++ < this.maxRetries) {
> try {
> return (pjp.proceed());
> }
> catch (final JDOUserException ex) {
> exception = ex;
>
> break; // fail
> }
> catch (final JDOCanRetryException ex) {
> exception = ex;
>
> // retry
> }
> catch (final JDOException ex) {
> exception = ex;
>
> /**
> * to quote Google's documentation: If any action
> * fails due to the requested entity group being in
> * use by another process, JDO throws a
> * JDODataStoreException or a JDOException, caused by a
> * java.util.ConcurrentModificationException.
> */
> if (!(ex.getCause() instanceof
> ConcurrentModificationException))
> break; // fail
>
> // retry
> }
>
> this.log.debug("retryCount: {}, exception: {}",
> Integer.valueOf(retryCount),
> ExceptionUtils.getFullStackTrace(exception));
> }
>
> throw (exception);
> }
>
>
> ted stockwell wrote:
>>
>> On Nov 17, 2:59 pm, Rusty Wright <[email protected]> wrote:
>>> Is there some way to pause before retrying the database transaction?
>>> If you don't, then it seems to me that the processes that are banging
>>> into each other are going to keep failing. I'd like to add a pause
>>> for a random amount of time in the catch block.
>>>
>>
>> It is not necessary to pause before retrying because if a transaction
>> fails with a 'RetryException' it is only because some other
>> transaction was committed and that other transaction made some changes
>> that are incompatible with the failed transactions changes.
>>
>> So... suppose you kick off 10 transactions at once.
>> At *most* only 9 of those transactions will fail with a
>> RetryException.
>> If you retry those 9 then at *most* 8 will fail, and so on....
>>
>>
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