Github user miguno commented on the pull request:
https://github.com/apache/storm/pull/268#issuecomment-73527901
I have improved the patch in this pull request, which particularly meant
modifications to
The updated patch is availabe at:
*
https://github.com/miguno/storm/commits/0.10.0-SNAPSHOT-STORM-392-miguno-merge
* The relevant commit is
https://github.com/miguno/storm/commit/8ebaaf8dbc63df3c2691e0cc3ac5102af7721ec3.
Code lineage: This improved patch includes the latest Storm 0.10.0-SNAPSHOT
code as of today, Feb 09. I used the patch in this pull request (#268) as the
basis, added my changes, and then pulled in the latest upstream Storm changes
for 0.10.0-SNAPSHOT via `git merge upstream/master`.
High-level changes:
- The great majority was refactoring the
[Client.java](https://github.com/apache/storm/blob/master/storm-core/src/jvm/backtype/storm/messaging/netty/Client.java)
in the Netty messaging backend. For instance, I removed unused imports,
obsolete code, clarified variables/methods, consolidated duplicate code, added
documentation, improved logging (which also helped me a lot while I was
bug-hunting), etc.
- I also introduced a few functional changes to the code in order to fix
the issue at hand. Notably, the new code can properly detect disconnects /
channel loss and trigger reconnect events. This also meant that the new code
is now more consistently verifying whether a channel from the client to the
server is truly `CONNECTED`. Also, we're now using a `ListenableFuture` instead
of a `Runnable` to handle the connection/reconnection logic, which leads to
cleaner and more readable code IMHO.
- I updated
[netty_unit_test.clj](https://github.com/apache/storm/blob/master/storm-core/test/clj/backtype/storm/messaging/netty_unit_test.clj)
so that all tests also wait until the Netty server and client instances are
ready (i.e. all of their connections are ready). This change was needed
because the original+improved STORM-329 patches modify Storm so that it will
ensure the readiness of server and client instances during the initial startup
of a topology, but the Netty unit tests are test-driving servers and clients
directly, so the tests couldn't rely on Storm's help.
Testing:
- The improved patch passes the full Storm's test suite.
- I have successfully tested a patched version of Storm 0.10.0-SNAPSHOT
(code as of today) in a Storm cluster via the aforementioned
storm-bolt-of-death topology.
- With the original patch, restarted bolt instances would not receive
new incoming data. With the improved patch the bolt instances start processing
new data immediately (as expected).
Next steps:
- I would appreciate any feedback of other developers on this improved
patch. I'd particularly appreciate any performance tests in addition to
functional tests. (I do not expect a performance degradation but of course I
might be wrong.)
- The storm-bolt-of-death topology to trigger the cascading failure should
be available by tomorrow for your testing convenience.
Many thanks again to @tedxia and @clockfly for the original patch, which
covered a lot (most?) of work already.
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