Errata

Code example has some missing statements:

import org.apache.zookeeper.WatchedEvent;
import java.io.IOException;

void startZK() throws IOException {
zk = new ZooKeeper(hostPort, 15000, this);
}

Note from the Author or Editor:
Add both import statements to the code snippet. The order of the imports should be:

import java.io.IOException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

In "case CONNECTIONLOSS" you invoke getWorkerList(); should be getWorkers()

Note from the Author or Editor:
In the code snippet of page 77, statement labeled with (2), it should be "getWorkers();".

Mentions getWorkerList, should be getWorkers

Note from the Author or Editor:
The description is correct, as per the code snippet, it should be getWorkers in the first sentence of the first paragraph of the page.

The second argument for zoo_acreate is text string of of the server_id, created by a call to snprintf. The third argument of zoo_acreate is supposed to be the length of the second argument, but it contains sizeof(int), not strlen(server_id_string) (or strtlen(server_id_string) + 1 if you want to store the trailing NUL). Since it is likely that the first 4 characters of the string of the random integer used as server_id will usually be unique, this will almost always work, but it isn't correct. It adds insult to injury that there is even a note that explains this incorrect behavior as passing in the length of an int due to the data being stored being an int.

The figure has a legend but the numbers are not in the figure itself.

Note from the Author or Editor:
The description is correct, Figure 9.4 has a legend with numbers, but the numbers aren't in the diagram. The numbers should simply follow the arrows. More specifically, (1) is for the leftmost arrows from S_2 to S_1 and S_3; (2) is for the middle arrows from S_1, S_3 to S_2; (3) is for the rightmost arrows from S_2 to S_1 and S_3.

The last sentence under weight.x=n should be under fsync.warningthresholdms knob.

Note from the Author or Editor:
Move the paragraph that starts with "If the sync system call takes too long..." to after the sentence that starts with "A ZooKeeper server will sync...".

The second paragraph under "fsync.warningthresholdms" should read:

A ZooKeeper server will sync a change to storage before it acknowledges the change. If the sync system call takes too long, system performance can be severely impacted. The server tracks the duration of this call and will issue a warning if it is taking longer than fsync.warningthresholdms. By default, it is 1,000 milliseconds.

Mentions terminateConnection (twice) but should be terminateSession.

Note from the Author or Editor:
On page 213, in the paragraph that starts with "In contrast...", there are two occurrences of terminateConnection and both occurrences need to be replaced with terminateSession.