Hello David Ribeiro Alves, Jean-Daniel Cryans,
I'd like you to do a code review. Please visit
http://gerrit.cloudera.org:8080/7494
to review the following change.
Change subject: KUDU-2053. Fix race in Java RequestTracker
......................................................................
KUDU-2053. Fix race in Java RequestTracker
The implementation of RequestTracker.newSeqNo() was previously
implemented as:
1. allocate the new sequence number
2. add that sequence number to the 'incomplete' map
These steps were individually thread-safe by using an AtomicLong and a
thread-safe collection, respectively, but they were not performed
atomically. Thus we could have the following race:
T1: allocate seq number 1
T2: allocate seq number 2
T2: add seq number 2 to incompleteRpcs
T2: ask for firstIncomplete() -> 2
T2: send an RPC
--> server GCs seqnum < 2
T1: add seq number 1 to incompleteRpcs
T1: send an RPC with seq number 1
--> server responds with an error since this seqnum is already
GCed
This patch fixes the issue by moving back to a simpler synchronization
scheme such that the two steps (allocation and addition to the tracking
structure) are done under a single critical section.
A new unit test is included which reliably reproduced the issue prior to
the fix.
Change-Id: I56f3d1ac85d34ca663e5b6378ff8362846a2424a
---
M java/kudu-client/src/main/java/org/apache/kudu/client/RequestTracker.java
M java/kudu-client/src/test/java/org/apache/kudu/client/TestRequestTracker.java
2 files changed, 70 insertions(+), 11 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/94/7494/1
--
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I56f3d1ac85d34ca663e5b6378ff8362846a2424a
Gerrit-PatchSet: 1
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Todd Lipcon <[email protected]>
Gerrit-Reviewer: David Ribeiro Alves <[email protected]>
Gerrit-Reviewer: Jean-Daniel Cryans <[email protected]>
