ferhui commented on pull request #393:
URL: https://github.com/apache/incubator-ratis/pull/393#issuecomment-760031039
Detail about this PR, I have post it to jira, and paste it here.
The first while clause in
TestRetryCacheWithGrpc#testRetryOnResourceUnavailableException
```
while (!failure.get()) {
long cid = callId;
r = cluster.newRaftClientRequest(clientId, leaderProxy.getId(), callId++,
new RaftTestUtil.SimpleMessage("message"));
CompletableFuture<RaftClientReply> f =
leaderProxy.submitClientRequestAsync(r);
f.exceptionally(e -> {
if (e.getCause() instanceof ResourceUnavailableException) {
RetryCacheTestUtil.isFailed(RetryCacheTestUtil.get(leader, clientId,
cid));
failure.set(true);
}
return null;
});
}
```
There are 2 requests here, and because followers call
blockWriteStateMachineData, the first request will be blocked, and
ELEMENT_LIMIT_KEY is 1, the second request will fail and receive
ResourceUnavailableException.
After quittng the first while clause. Followers call
unblockWriteStateMachineData
In the second while clause
```
while (failure.get()) {
try {
// retry until the request failed with ResourceUnavailableException
succeeds.
leaderProxy.submitClientRequestAsync(r).get();
} catch (Exception e) {
failure.set(false);
}
}
```
There are 2 cases: 1. If the first request has been done, the 3rd request
will be handled, and later requests will hit retrycache, and server will always
return success. It couldn't get Exception and enter infinite loop. 2. If the
first request hasn't been done, and the 3rd request has been reach the server,
it will get ResourceUnavailableException and set failure true, and quit the
loop.
Mostly the case 1 occurs, and this UT nearly always fails
So i suggest that quit the loop when request handled successfully as the
comments say
> // retry until the request failed with ResourceUnavailableException
succeeds.
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