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_r167131090
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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())
+ .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);
+
}
};
/**
- * Each thread local buffered read channel can share the same file handle
because reads are not relative
- * and don't cause a change in the channel's position. We use this map to
store the file channels. Each
- * file channel is mapped to a log id which represents an open log file.
+ * FileChannelBackingCache used to cache RefCntFileChannels for read.
+ * In order to avoid get released file, adopt design of
FileInfoBackingCache.
+ * @see FileInfoBackingCache
*/
- private final ConcurrentMap<Long, FileChannel> logid2FileChannel = new
ConcurrentHashMap<Long, FileChannel>();
+ class FileChannelBackingCache {
+ static final int DEAD_REF = -0xdead;
+
+ final ConcurrentHashMap<Long, CachedFileChannel> fileChannels = new
ConcurrentHashMap<>();
+
+ CachedFileChannel loadFileChannel(long logId) throws IOException {
+ CachedFileChannel cachedFileChannel = fileChannels.get(logId);
+ if (cachedFileChannel != null) {
+ boolean retained = cachedFileChannel.tryRetain();
Review comment:
um, that's right. The ReadWriteLock is necessary, I'll refactor again. I
thought that lock is used to guarantee FileInfo's file open/write operations
before now.
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