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_r167209456
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File path:
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogger.java
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@@ -330,54 +333,216 @@ 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((Long)
removal.getKey()).release())
Review comment:
I think that adding a readLock when getting value from
FileChannelBackingCache has the same effect, and that has little change to
BufferedReadChannel. I prefer to this one, which one is better in your opinion?
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