qdrouterd accumulates memory on connections with link attach+detach loop

Particular reproducer: python script (non-threaded version): import random from proton.utils import BlockingConnection from time import sleep from uuid import uuid4   ROUTER_ADDRESS = "proton+amqp://0.0.0.0:5672" ADDRESS = "test.address" HEARTBEAT = 5 SLEEP_MIN = 0.1 SLEEP_MAX = 0.2   conn = BlockingConnection(ROUTER_ADDRESS, ssl_domain=None, heartbeat=HEARTBEAT)   while True: recv = conn.create_receiver('%s' %(ADDRESS), name=str(uuid4()), dynamic=False, options=None) sleep(random.uniform(SLEEP_MIN,SLEEP_MAX)) recv.close() sleep(random.uniform(SLEEP_MIN,SLEEP_MAX)) threaded version for faster reproducer: import random import threading from proton.utils import BlockingConnection from time import sleep from uuid import uuid4   ROUTER_ADDRESS = "proton+amqp://0.0.0.0:5672" ADDRESS = "test.address" HEARTBEAT = 5 SLEEP_MIN = 0.1 SLEEP_MAX = 0.2 THREADS = 40 ADDRESSES = 20   class ReceiverThread(threading.Thread): def __init__(self, address=ADDRESS): super(ReceiverThread, self).__init__() self.address = address   def run(self): self.conn = BlockingConnection(ROUTER_ADDRESS, ssl_domain=None, heartbeat=HEARTBEAT) while True: self.recv = self.conn.create_receiver('%s' %(self.address), name=str(uuid4()), dynamic=False, options=None) sleep(random.uniform(SLEEP_MIN,SLEEP_MAX)) self.recv.close() sleep(random.uniform(SLEEP_MIN,SLEEP_MAX))   threads = [] for i in range(THREADS): threads.append(ReceiverThread('%s.%s' %(ADDRESS, i%ADDRESSES))) threads[i].start()   for i in range(THREADS): threads[i].join() # technically, we will never pass this line Run that script and observe memory utilization. Another diagnostic step requires gdb - before killing the reproducer script, run: gdb -p $(pgrep qdrouterd) $(which qdrouterd) add breakpoint to pn_list_remove. Then kill the reproducer and breakpoint will show backtrace: #0 pn_list_remove (list=0x244a1b0, value=value@entry=0x23b19a0) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/core/object/list.c:97 #1 0x00007fd029595615 in pni_remove_link (ssn=0x2449b20, link=0x23b19a0) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/core/engine.c:310 #2 0x00007fd029597b38 in pn_link_free (link=0x23b19a0) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/core/engine.c:351 #3 0x00007fd029597bc3 in pn_session_free (session=0x2449b20) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/core/engine.c:270 #4 0x00007fd029597c7c in pn_connection_release (connection=connection@entry=0x7fd00c02fc30) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/core/engine.c:124 #5 0x00007fd029597cd9 in pn_connection_free (connection=0x7fd00c02fc30) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/core/engine.c:145 #6 0x00007fd029594cc6 in pn_connection_driver_destroy (d=d@entry=0x7fd00cf96608) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/core/connection_driver.c:93 #7 0x00007fd0293746cc in pconnection_final_free (pc=pc@entry=0x7fd00cf96060) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/proactor/epoll.c:827 #8 0x00007fd029375544 in pconnection_cleanup (pc=pc@entry=0x7fd00cf96060) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/proactor/epoll.c:843 #9 0x00007fd029376532 in pconnection_process (pc=0x7fd00cf96060, events=<optimized out>, events@entry=0, timeout=timeout@entry=true, topup=topup@entry=false) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/proactor/epoll.c:1178 #10 0x00007fd029376f1b in proactor_do_epoll (p=0x2263eb0, can_block=can_block@entry=true) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/proactor/epoll.c:2013 #11 0x00007fd029377e9a in pn_proactor_wait (p=<optimized out>) at /usr/src/debug/qpid-proton-0.22.0/proton-c/src/proactor/epoll.c:2028 #12 0x00007fd0298065a9 in thread_run (arg=0x226e260) at /usr/src/debug/qpid-dispatch-1.0.0/src/server.c:932 #13 0x00007fd02915ce25 in start_thread (arg=0x7fd016ffd700) at pthread_create.c:308 #14 0x00007fd02849034d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113 where "p list->size" shows arbitrary high numer (despite there is up to 1 link on each connection only).

In previous versions of AMQ Interconnect, a defect caused memory usage to build up when a long-lived connection carried many link attaches and detaches. The memory for the links was not freed until the connection was closed. This defect has been corrected, and link memory is reclaimed when the link is closed.