sonatype-lift[bot] commented on a change in pull request #592:
URL: https://github.com/apache/solr/pull/592#discussion_r800033599
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File path: solr/core/src/java/org/apache/solr/search/SolrIndexSearcher.java
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@@ -865,9 +936,26 @@ public BitDocSet getLiveDocSet() throws IOException {
// Going through the filter cache will provide thread safety here if we
only had getLiveDocs,
// but the addition of setLiveDocs means we needed to add volatile to
"liveDocs".
BitDocSet docs = liveDocs;
- if (docs == null) {
- //note: maybe should instead calc manually by segment, using
FixedBitSet.copyOf(segLiveDocs); avoid filter cache?
- liveDocs = docs = getDocSetBits(matchAllDocsQuery);
+ if (docs != null) {
+ matchAllDocsCacheHitCount.incrementAndGet();
+ } else {
+ synchronized (matchAllDocsCacheComputationTracker) {
+ if (liveDocsFuture != null) {
+ // use future if it already exists
+ assert matchAllDocsCacheComputationTracker.incrementAndGet() > 0;
+ } else {
+ // otherwise create the initial/only future, and run it inline
+ assert matchAllDocsCacheComputationTracker.getAndSet(0) ==
Long.MIN_VALUE;
+ liveDocsFuture = new FutureTask<>(this::computeLiveDocs);
+ liveDocsFuture.run(); // first caller will block execution here
+ }
+ }
+ try {
+ docs = liveDocsFuture.get(); // subsequent callers block here, waiting
for initial/only execution to complete
Review comment:
*THREAD_SAFETY_VIOLATION:* Read/Write race. Non-private method
`SolrIndexSearcher.getLiveDocSet()` reads without synchronization from
`this.liveDocsFuture`. Potentially races with write in method
`SolrIndexSearcher.getDocSetNC(...)`.
Reporting because this access may occur on a background thread.
(at-me [in a reply](https://help.sonatype.com/lift/talking-to-lift) with
`help` or `ignore`)
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