hanm commented on a change in pull request #1051: Add server side large request
throttling
URL: https://github.com/apache/zookeeper/pull/1051#discussion_r313147680
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File path:
zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServer.java
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@@ -221,6 +221,37 @@
private RequestThrottler requestThrottler;
public static final String SNAP_COUNT = "zookeeper.snapCount";
+ /**
+ * This setting sets a limit on the total number of large requests that
+ * can be inflight and is designed to prevent ZooKeeper from accepting
+ * too many large requests such that the JVM runs out of usable heap and
+ * ultimately crashes.
+ *
+ * The limit is enforced by the {@link checkRequestSize(int, boolean)}
+ * method which is called by the connection layer ({@link NIOServerCnxn},
+ * {@link NettyServerCnxn}) before allocating a byte buffer and pulling
+ * data off the TCP socket. The limit is then checked again by the
+ * ZooKeeper server in {@link processPacket(ServerCnxn, ByteBuffer)} which
+ * also atomically updates {@link currentLargeRequestBytes}. The request is
+ * then marked as a large request, with the request size stored in the
Request
+ * object so that it can later be decremented from {@link
currentLargeRequestsBytes}.
+ *
+ * When a request is completed or dropped, the relevant code path calls the
+ * {@link requestFinished(Request)} method which performs the decrement if
+ * needed.
+ */
+ private volatile int largeRequestMaxBytes =
+ Integer.getInteger("zookeeper.largeRequestMaxBytes", 100 * 1024 *
1024);
+
+ /**
+ * The size threshold after which a request is considered a large request
+ * and is checked against the large request byte limit.
+ */
+ private volatile int largeRequestThreshold =
Review comment:
I think it's necessary to do a validation of the values on these two newly
added property, and throw argument exceptions if they are off the chart (and
update doc to reflect the valid ranges.).
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