jeffkbkim commented on code in PR #17221:
URL: https://github.com/apache/kafka/pull/17221#discussion_r1772963066
##########
coordinator-common/src/test/java/org/apache/kafka/coordinator/common/runtime/HdrHistogramTest.java:
##########
@@ -172,4 +177,39 @@ public void testHistogramDataReset() {
assertEquals(numEventsInFirstCycle, hdrHistogram.count(now +
maxSnapshotAgeMs));
assertEquals(numEventsInSecondCycle, hdrHistogram.count(now + 1 +
maxSnapshotAgeMs));
}
+
+ @Test
+ public void testLatestHistogramRace() throws InterruptedException,
ExecutionException {
+ long maxSnapshotAgeMs = 10L;
+ long now = System.currentTimeMillis();
+ HdrHistogram hdrHistogram = new HdrHistogram(maxSnapshotAgeMs,
MAX_VALUE, 1);
+ ExecutorService countExecutor = Executors.newFixedThreadPool(2);
+ for (int i = 1; i < 10000; i++) {
+ int numEvents = 2;
+ for (int j = 0; j < numEvents; j++) {
+ hdrHistogram.record(i);
+ }
+ final long moreThanMaxAge = now + maxSnapshotAgeMs + 1;
+ now = moreThanMaxAge;
+ CountDownLatch latch = new CountDownLatch(1);
+ Callable<Long> countTask = () -> {
+ try {
+ assertTrue(latch.await(500, TimeUnit.MILLISECONDS));
+ return hdrHistogram.count(moreThanMaxAge);
+ } catch (InterruptedException e) {
+ throw new RuntimeException(e);
+ }
+ };
+ Future<Long> t1Future = countExecutor.submit(countTask);
+ Future<Long> t2Future = countExecutor.submit(countTask);
+ latch.countDown();
+ long t1Count = t1Future.get();
+ long t2Count = t2Future.get();
+ assertTrue(
+ numEvents == t1Count && numEvents == t2Count,
Review Comment:
ah, i understand where i got confused - with this PR a call to
`latestHistogram()` will always return a MAX_AGE_SNAPSHOT worth of data (as it
should). thanks for the explanation!
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