google-cloud-logging: LoggingImpl.pendingWrites remove before add (with suggested fix) #4668
Description
In LoggingImpl, it is possible to leak memory in pendingWrites, if the future completes before the callback is added. If so, the callback runs before the call to pendingWrites.remove()
@Test
public void testMemoryLeak() {
WriteLogEntriesRequest request =
WriteLogEntriesRequest.newBuilder()
.addAllEntries(
Iterables.transform(
ImmutableList.of(LOG_ENTRY1, LOG_ENTRY2), LogEntry.toPbFunction(PROJECT)))
.build();
WriteLogEntriesResponse response = WriteLogEntriesResponse.newBuilder().build();
EasyMock.expect(loggingRpcMock.write(request)).andStubReturn(ApiFutures.immediateFuture(response));
EasyMock.replay(rpcFactoryMock, loggingRpcMock);
logging = options.getService();
LoggingImpl impl = (LoggingImpl) logging;
assertEquals(0, impl.pendingWrites.size());
for (int i = 0; i < 1000; i++) {
logging.write(ImmutableList.of(LOG_ENTRY1, LOG_ENTRY2));
}
logging.flush();
assertEquals(0, impl.pendingWrites.size());
}A proposed fix is to move this code to between creating the future and adding the callback.
synchronized (writeLock) {
pendingWrites.add(writeFuture);
}