arp7 commented on a change in pull request #948: HDDS-1649. On installSnapshot
notification from OM leader, download checkpoint and reload OM state
URL: https://github.com/apache/hadoop/pull/948#discussion_r293597766
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File path:
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/ratis/OzoneManagerStateMachine.java
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@@ -171,6 +168,22 @@ public long takeSnapshot() throws IOException {
return 0;
}
+ /**
+ * Leader OM has purged entries from its log. To catch up, OM must download
+ * the latest checkpoint from the leader OM and install it.
+ * @param firstTermIndexInLog TermIndex of the first append entry available
+ * in the Leader's log.
+ * @return the last term index included in the installed snapshot.
+ */
+ public CompletableFuture<TermIndex> notifyInstallSnapshotFromLeader(
+ TermIndex firstTermIndexInLog) {
+ // TODO: Raft server should send the leaderId
+ String leaderId = null;
+ CompletableFuture<TermIndex> future = CompletableFuture
+ .supplyAsync(() -> ozoneManager.installSnapshot(leaderId));
Review comment:
We should not execute this in the default ForkJoinPool. That can suffer from
thread exhaustion/deadlock issues since there are very few threads in the
default pool.
Instead use the overload of `supplyAsync` that accepts an `Executor`.
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