Re: [infinispan-dev] PutForExternalRead and autoCommit

On Nov 17, 2011, at 4:39 PM, Slorg1 wrote: > Hi all, > > See comment below, > > On Thu, Nov 17, 2011 at 10:20, Galder Zamarreño <galder(a)redhat.com&gt; wrote: >> >> On Nov 17, 2011, at 2:54 PM, Manik Surtani wrote: >> >>> On 17 Nov 2011, at 09:30, Galder Zamarreño wrote: >>> >>>> Hi, >>>> >>>> Forcing caches to be either transactional or non transactional caches causes some issues with operations such as putForExternalRead with default configuration options. >>>> >>>> Assuming we have a transactional cache, if autoCommit is on (default), putForExternalRead will: >>>> 1. Suspend the ongoing transaction >>>> 2. Will create a brand new transaction due to implicit transaction creation logic in auto commit. >>>> >>>> This is not good. >>> >>> What's not good about this? 1 is by design and is correct behaviour. 2 should not affect anything, since the new tx is completed at the end of the PFER invocation. >> >> 2 does not affect anything but seems wasteful to me. Why start a transaction when I don't need one? > > I do not understand the need for #1 to happen given that a running > transaction already exist. In the case of a replicated cache, that > transaction exists remotely on all other nodes. > Thus why not apply the put under the same scope ? It's an optimisation since we're reading from the external source of data. This optimisation avoids locking issues as a result of trying to read the same piece of data into the cache when executed concurrently in different nodes. Read the putForExternal read javadoc to find out more.