Fix concurrent requests race over scroll context limit (#53449)

Concurrent search scroll requests can lead to more scroll contexts than the limit.
This commit is contained in:
Nhat Nguyen 2020-03-12 11:51:16 -04:00
parent 2789fe4179
commit fe2f6b359e
2 changed files with 48 additions and 8 deletions

View File

@ -642,7 +642,6 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
boolean success = false;
try {
if (context.scrollContext() != null) {
openScrollContexts.incrementAndGet();
context.indexShard().getSearchOperationListener().onNewScrollContext(context);
}
context.indexShard().getSearchOperationListener().onNewContext(context);
@ -661,14 +660,15 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
final SearchContext createContext(SearchRewriteContext rewriteContext) throws IOException {
final DefaultSearchContext context = createSearchContext(rewriteContext, defaultSearchTimeout);
try {
if (rewriteContext.request != null && openScrollContexts.get() >= maxOpenScrollContext) {
final ShardSearchRequest request = rewriteContext.request;
if (request.scroll() != null) {
context.addReleasable(openScrollContexts::decrementAndGet, Lifetime.CONTEXT);
if (openScrollContexts.incrementAndGet() > maxOpenScrollContext) {
throw new ElasticsearchException(
"Trying to create too many scroll contexts. Must be less than or equal to: [" +
maxOpenScrollContext + "]. " + "This limit can be set by changing the ["
+ MAX_OPEN_SCROLL_CONTEXT.getKey() + "] setting.");
}
final ShardSearchRequest request = rewriteContext.request;
if (request.scroll() != null) {
context.scrollContext(new ScrollContext());
context.scrollContext().scroll = request.scroll();
}
@ -768,7 +768,6 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
assert activeContexts.containsKey(context.id().getId()) == false;
context.indexShard().getSearchOperationListener().onFreeContext(context);
if (context.scrollContext() != null) {
openScrollContexts.decrementAndGet();
context.indexShard().getSearchOperationListener().onFreeScrollContext(context);
}
}

View File

@ -539,6 +539,47 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
ex.getMessage());
}
public void testOpenScrollContextsConcurrently() throws Exception {
createIndex("index");
final IndicesService indicesService = getInstanceFromNode(IndicesService.class);
final IndexShard indexShard = indicesService.indexServiceSafe(resolveIndex("index")).getShard(0);
final int maxScrollContexts = SearchService.MAX_OPEN_SCROLL_CONTEXT.get(Settings.EMPTY);
final SearchService searchService = getInstanceFromNode(SearchService.class);
Thread[] threads = new Thread[randomIntBetween(2, 8)];
CountDownLatch latch = new CountDownLatch(threads.length);
for (int i = 0; i < threads.length; i++) {
threads[i] = new Thread(() -> {
latch.countDown();
try {
latch.await();
for (; ; ) {
SearchService.SearchRewriteContext rewriteContext =
searchService.acquireSearcherAndRewrite(new ShardScrollRequestTest(indexShard.shardId()), indexShard);
try {
searchService.createAndPutContext(rewriteContext);
} catch (ElasticsearchException e) {
assertThat(e.getMessage(), equalTo(
"Trying to create too many scroll contexts. Must be less than or equal to: " +
"[" + maxScrollContexts + "]. " +
"This limit can be set by changing the [search.max_open_scroll_context] setting."));
return;
}
}
} catch (Exception e) {
throw new AssertionError(e);
}
});
threads[i].setName("elasticsearch[node_s_0][search]");
threads[i].start();
}
for (Thread thread : threads) {
thread.join();
}
assertThat(searchService.getActiveContexts(), equalTo(maxScrollContexts));
searchService.freeAllScrollContexts();
}
public static class FailOnRewriteQueryPlugin extends Plugin implements SearchPlugin {
@Override
public List<QuerySpec<?>> getQueries() {