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Increase the default backlog of listen() to net.core.somaxconn of Linux. #2461

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Increase the default backlog of listen() to net.core.somaxconn of Linux. #2461

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86ac52b
Increase the default backlog of listen() to net.core.somaxconn of Linux.
wenjianhn Sep 23, 2026
fb122ed
Increase the default backlog of listen of reconfigure()
wenjianhn Oct 14, 2026
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4 changes: 2 additions & 2 deletions zookeeper-server/src/main/java/org/apache/zookeeper/server/NIOServerCnxnFactory.java
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Original file line number Diff line number Diff line change
Expand Up @@ -659,7 +659,7 @@ public void configure(InetSocketAddress addr, int maxcc, int backlog, boolean se
ss.socket().setReuseAddress(true);
LOG.info("binding to port {}", addr);
if (listenBacklog == -1) {
ss.socket().bind(addr);
ss.socket().bind(addr, Integer.MAX_VALUE);
} else {
ss.socket().bind(addr, listenBacklog);
}
Expand Down Expand Up @@ -695,7 +695,7 @@ public void reconfigure(InetSocketAddress addr) {
this.ss = ServerSocketChannel.open();
ss.socket().setReuseAddress(true);
LOG.info("binding to port {}", addr);
ss.socket().bind(addr);
ss.socket().bind(addr, listenBacklog == -1 ? Integer.MAX_VALUE : listenBacklog);
ss.configureBlocking(false);
acceptThread = new AcceptThread(ss, addr, selectorThreads);
acceptThread.start();
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5 changes: 3 additions & 2 deletions ...ges/_docs/docs/_mdx/admin-ops/administrators-guide/configuration-parameters.mdx
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Expand Up @@ -430,8 +430,9 @@ property, when available, is noted below.
the number of requests that will be queued server-side to be processed
by the ZooKeeper server. Connections that exceed this length will receive
a network timeout (30s) which may cause ZooKeeper session expiry issues.
By default, this value is unset (`-1`) which, on Linux, uses a backlog of
`50`. This value must be a positive number.
By default, this value is unset (`-1`) which, on Linux, is
net.core.somaxconn that defaults to 4096 since Linux 5.4. This value
must be a positive number.

- _serverCnxnFactory_ :
(Java system property: **zookeeper.serverCnxnFactory**)
Expand Down