@Override
  protected void doCall() throws Exception {
    LOG.info("Received a replay sync replication wals {} event, peerId={}", wals, peerId);
    if (rs.getReplicationSinkService() != null) {
      Lock peerLock = peersLock.acquireLock(wals.get(0));
      try {
        for (String wal : wals) {
          replayWAL(wal);
        }
      } finally {
        peerLock.unlock();
      }
    }
  }
This callable executed at RS side to replay sync replication wal.
hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplaySyncReplicationWALCallable.java