iamcaoxudong commented on a change in pull request #1700: HDFS-14963. Add HDFS
Client machine caching active namenode index mechanism.
URL: https://github.com/apache/hadoop/pull/1700#discussion_r350013195
##########
File path:
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/ConfiguredFailoverProxyProvider.java
##########
@@ -93,4 +109,65 @@ public synchronized void close() throws IOException {
public boolean useLogicalURI() {
return true;
}
+
+ /**
+ * Write active NameNode index to cache file.
+ */
+ public void writeActiveCache(int index) {
+ if (!cacheActiveEnabled) {
+ return;
+ }
+
+ synchronized (cacheActiveFile) {
+ boolean exist = cacheActiveFile.exists();
+ try (RandomAccessFile raf = new RandomAccessFile(cacheActiveFile, "rw");
+ FileChannel fc = raf.getChannel();
+ FileLock lock = fc.tryLock(0, Long.MAX_VALUE, false)) {
+ if (lock != null) {
+ raf.setLength(0);
+ raf.writeBytes(String.valueOf(index));
+ if (!exist) {
+ boolean ret = cacheActiveFile.setWritable(true, false)
+ && cacheActiveFile.setReadable(true, false);
+ if (!ret) {
+ throw new IOException("Cannot set file rw mode.");
+ }
+ }
+ LOG.debug("Succeed in writing active index " + index
+ + " to cache file " + cacheActiveFile);
+ }
+ } catch (Throwable e) {
+ LOG.warn("Filed to write active index " + index + " to cache file "
+ + cacheActiveFile, e);
+ }
+ }
+ }
+
+ /**
+ * Read active NameNode index from cache file.
+ */
+ public int readActiveCache() {
+ if (!cacheActiveEnabled) {
+ return 0;
+ }
+
+ int index = 0;
+ synchronized (cacheActiveFile) {
+ if (!cacheActiveFile.exists()) {
+ return 0;
+ }
+
+ try (RandomAccessFile raf = new RandomAccessFile(cacheActiveFile, "rw");
+ FileChannel fc = raf.getChannel();
+ FileLock lock = fc.tryLock(0, Long.MAX_VALUE, true)) {
+ if (lock != null) {
+ index = Integer.parseInt(raf.readLine()) % proxies.size();
+ }
+ } catch (Throwable e) {
+ LOG.warn("Failed to read active index from cache file "
+ + cacheActiveFile + ", will begin from index 0.", e);
Review comment:
OK, thanks, I have added it like this:
2019-11-25 14:52:11,678 WARN ha.AbstractNNFailoverProxyProvider: Failed to
read active index from cache file /tmp/ns1, It may be due to permission issues,
the dfs.client.failover.cache-active.dir must be properly configured! Now we
will begin from index 0.
java.io.FileNotFoundException: /tmp/ns1 (Permission denied)
at java.io.RandomAccessFile.open0(Native Method)
at java.io.RandomAccessFile.open(RandomAccessFile.java:316)
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:243)
...
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