[QPID-7149] [HA] active HA broker memory leak when ring queue discards overflow messages

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: qpid-cpp-1.35.0
• Component/s: C++ Broker

Environment

RHEL6

qpid trunk svn rev. 1735384

• issue seen in very old releases (since active-passive HA cluster initial implementation, most probably)

libstdc++-devel-4.4.7-4.el6.x86_64
gcc-c++-4.4.7-4.el6.x86_64
libgcc-4.4.7-4.el6.x86_64
libstdc++-4.4.7-4.el6.x86_64
gcc-4.4.7-4.el6.x86_64

• Assignee: Alan Conway
• Reporter: Pavel Moravec
• Created: 17/Mar/16 12:09
• Updated: 06/Sep/16 21:32
• Resolved: 17/Jun/16 18:22

Description

There is a memory leak on active HA broker, triggered most probably by purging overflow message from a ring queue. Basic scenario is to setup HA cluster, promote to primary and feed forever a ring queue with messages.

Detailed scenario:

1) Start brokers and promote one to primary:

start_broker() {
	port=$1
	shift
	rm -rf _${port}
	mkdir _${port}
	nohup qpidd --load-module=ha.so --port=$port --log-to-file=qpidd.$port.log --data-dir=_${port} --auth=no --log-to-stderr=no --ha-cluster=yes --ha-brokers-url="$(hostname):5672,$(hostname):5673,$(hostname):5674" --ha-replicate=all --acl-file=/root/qpidd.acl "$@" > /dev/null 2>&1 &
	sleep 1
}


killall qpidd qpid-receive 2> /dev/null
rm -f qpidd.*.log
start_broker 5672
sleep 1
qpid-ha promote -b $(hostname):5672 --cluster-manager
sleep 1
start_broker 5673
sleep 1
start_broker 5674

2) Create ring queues and send there messages (it is enough to have 1 queue, having more should show the leak faster):

for i in $(seq 0 9); do
	qpid-config add queue FromKeyServer_$i --max-queue-size=10000 --max-queue-count=10 --limit-policy=ring --argument=x-qpid-priorities=10
done

while true; do
	for j in $(seq 1 10); do
		for i in $(seq 1 10); do
			for k in $(seq 0 9); do
				qpid-send -a FromKeyServer_$k -m 100 --send-rate=50 -- priority=$(($((RANDOM))%10)) &
			done
		done
		wait
		while [ $(qpid-stat -q | grep broker-replicator | sed "s/Y//g" | awk '{ print $2 }' | sort -n | tail -n1) != "0" ]; do
			sleep 1
		done
	done
	date
	ps aux | grep qpidd | grep "port=5672" | awk -F "--store-dir" '{ print $1 }'
done

(the "while [ $(qpid-stat -q | .." cycle is there just to slow down the message enqueues to ensure replication federation queues dont have big backlog - that would interfere with memory consumpiton observation)

3) Run those scripts and monitor memory consumption.

• without using priority queues and sending messages without priorities, leak is evident as well - sometimes smaller, sometimes the same
• valgrind (on some older versions I tested before more thoroughly) detects nothing (neither leaked memory or reachable at shutdown)
• same leak is evident even with --ha-replicate=none
• number of backup brokers does not affect the memory leak

Issue Links

• is duplicated by: QPID-7150 HA memory leak in primary broker when overwriting messages in a ring queue