ArvinDevel commented on a change in pull request #832: Issue 620: Close the
fileChannels for read when they are idle
URL: https://github.com/apache/bookkeeper/pull/832#discussion_r163567948
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File path:
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogger.java
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@@ -330,54 +334,115 @@ private int readFromLogChannel(long entryLogId,
BufferedReadChannel channel, Byt
* A thread-local variable that wraps a mapping of log ids to
bufferedchannels
* These channels should be used only for reading. logChannel is the one
* that is used for writes.
+ * We use this Guava cache to store the BufferedReadChannel.
+ * When the BufferedReadChannel is removed, the underlying fileChannel's
refCnt decrease 1,
+ * temporally use 1h to relax replace after reading.
*/
- private final ThreadLocal<Map<Long, BufferedReadChannel>> logid2Channel =
- new ThreadLocal<Map<Long, BufferedReadChannel>>() {
+ private final ThreadLocal<Cache<Long, BufferedReadChannel>> logid2Channel =
+ new ThreadLocal<Cache<Long, BufferedReadChannel>>() {
@Override
- public Map<Long, BufferedReadChannel> initialValue() {
+ public Cache<Long, BufferedReadChannel> initialValue() {
// Since this is thread local there only one modifier
// We dont really need the concurrency, but we need to use
// the weak values. Therefore using the concurrency level of 1
- return new MapMaker().concurrencyLevel(1)
- .weakValues()
- .makeMap();
+ return CacheBuilder.newBuilder().concurrencyLevel(1)
+ .expireAfterAccess(readChannelCacheExpireTimeMs,
TimeUnit.MILLISECONDS)
+ //decrease the refCnt
+ .removalListener(removal ->
logid2FileChannel.get(removal.getKey()).release())
+ .build(readChannelLoader);
+ }
+ };
+
+ @VisibleForTesting
+ long getReadChannelCacheExpireTimeMs() {
+ return readChannelCacheExpireTimeMs;
+ }
+
+ @VisibleForTesting
+ CacheLoader<Long, BufferedReadChannel> getReadChannelLoader() {
+ return readChannelLoader;
+ }
+
+ private final CacheLoader<Long, BufferedReadChannel> readChannelLoader =
+ new CacheLoader<Long, BufferedReadChannel> () {
+ public BufferedReadChannel load(Long entryLogId) throws Exception {
+
+ return getChannelForLogId(entryLogId);
+
}
};
+ static class ReferenceCountedFileChannel extends AbstractReferenceCounted {
+ private final FileChannel fc;
+
+ public ReferenceCountedFileChannel(FileChannel fileChannel) {
+ this.fc = fileChannel;
+ }
+
+ @VisibleForTesting
+ FileChannel getFileChannel(){
+ return fc;
+ }
+
+ @Override
+ public ReferenceCounted touch(Object hint) {
+ return this;
+ }
+
+ // when the refCnt decreased to 0 or force deallocate
+ @Override
+ protected void deallocate() {
+ try {
+ fc.close();
Review comment:
@ivankelly I have fixed your comment. I'm not sure whether it still has race
condition, please has a review. If it still has race condition, I'll try use
your design in #913. And the last resort can be removing hashMap and use
multiple fileChannel directly.
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