Setup

1. Setup the folowing topology with base DN dc=example,dc=com:

• DSRS (generate 100 entries)
• DS1
• DS2
• DS3
• DS4
• ... (add as many directory servers as you want to speed up the appearance of the problem)

2. Run initialize-all on DSRS
3. For each server, add an entry. See down below and replace the following:

• the port number should match each directory server's port
• replace "A1" in the dn to create unique entries for each directory server (for example "A2", "A3", "A4", ...)

$ DS1/bin/ldapmodify -p 1501 -D "cn=Directory Manager" -w password -a <<END_OF_COMMAND_INPUT
dn: cn=A1,dc=example,dc=com
objectclass:top
objectclass:organizationalperson
objectclass:inetorgperson
objectclass:person
sn:User
cn:Test User
description:1
description:2
mail:bla@example.com
telephonenumber:+33165990803
END_OF_COMMAND_INPUT

4. Run stop-ds for DS1, DS2, DS3, DS4, ... (Do not stop DSRS)

5. Run modrate on DSRS:

$ opendj-ldap-toolkit/bin/modrate -p 1500 -D "cn=directory manager" -w password -F -c 4 -t 4 -b "uid=user.%d,ou=people,dc=example,dc=com" -g "rand(0,1000)" -g "randstr(16)" 'description:%2$s'

and let it run...

6. start-ds DS1

Wait for the replication server to get blocked

Run the following commands to monitor the evolution:

1. On DS1, wait for current-rcv-window attribute to reach 0

   $ watch 'DS1/bin/ldapsearch -p 1501 -D "cn=Directory Manager" -w password -b "cn=monitor" "(replayed-updates=*)" max-rcv-window current-rcv-window replayed-updates'
   

   Sample output:

   dn: cn=Directory server DS(22105) localhost:59784,cn=dc_example_dc_com,cn=Replic
    ation,cn=monitor
   max-rcv-window: 100000
   current-rcv-window: 0
   replayed-updates: 1699902
   

1. On DSRS, wait for a thread to be blocked on ServerHandler.acquirePermitInSendWindow()

   $ watch 'jstack `cat target/opendj_0_DSRS/logs/server.pid` | grep acquirePermitInSendWindow -B8 -A3'
   

   Sample output:

   "Replication server RS(31258) writing to Replica DS(22105) for domain "dc=example,dc=com" at localhost/127.0.0.1:5978
   4" #314 prio=5 os_prio=0 tid=0x00007fd66c090800 nid=0x6ae0 waiting on condition [0x00007fd645fa2000]
      java.lang.Thread.State: TIMED_WAITING (parking)
           at sun.misc.Unsafe.park(Native Method)
           - parking to wait for  <0x00000006ceabb5a8> (a java.util.concurrent.Semaphore$NonfairSync)
           at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
           at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedNanos(AbstractQueuedSynchronizer.java
   :1037)
           at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.jav
   a:1328)
           at java.util.concurrent.Semaphore.tryAcquire(Semaphore.java:409)
           at org.opends.server.replication.server.ServerHandler.acquirePermitInSendWindow(ServerHandler.java:951)
           at org.opends.server.replication.server.ServerHandler.take(ServerHandler.java:929)
           at org.opends.server.replication.server.ServerWriter.run(ServerWriter.java:94)