Wenxiang Qiu created DIRSERVER-2234:
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Summary: Kinit via TCP causes ApacheDS to create a NioProcessor
thread at 100% CPU
Key: DIRSERVER-2234
URL: https://issues.apache.org/jira/browse/DIRSERVER-2234
Project: Directory ApacheDS
Issue Type: Bug
Affects Versions: 2.0.0-M24
Environment: ApacheDS
Reporter: Wenxiang Qiu
ApacheDS uses a KerberosProtocolHandler as the handler of the
IoAcceptor in KdcServer.java:
{code:java}
// Inject the protocol handler acceptor.setHandler( new
KerberosProtocolHandler( this, store ) );
{code}
When a TCP connection is about to be closed,
KerberosProtocolHandler$inputClosed(IoSession session) is invoked when
{code:java}
filterChain.fireInputClosed();
{code}
is reached in AbstractPollingIoProcessor.java. But
KerberosProtocolHandler$inputClosed(IoSession session) does nothing:
{code:java}
public void inputClosed( IoSession session )
{
}
{code}
which leaves the session unclosed, which in turn prevents its SocketChannel
from being deregistered from the selector in NioProcessor. As a result,
{code:java}
int selected = select(SELECT_TIMEOUT);
{code}
in AbstractPollingIoProcessor.Processor.run() keeps returning a readable
channel, on which read() returns -1. This infinite loop consumes all available
CPU.
By constrast, LdapServer sets a LdapProtocolHandler to its acceptor, and
LdapProtocolHandler inherits inputClosed(IoSession session) from
IoHandlerAdapter:
{code:java}
public void inputClosed(IoSession session) throws Exception {
session.close(true);
}
{code}
which closes properly the session.
How to reproduce:
Simply run kinit with TCP (by setting udp_preference_limit = 1 in
/etc/krb5.conf), and ApacheDS will be running at 100% CPU. Doing it again will
consume more CPU resources depending on core number.
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