[lttng-dev] High memory consumption issue on RCU side

[Evgeniy Ivanov]

Hi all,

I'm investigating high memory usage of my program: RSS varies between
executions in range 20-50 GB, though it should be determenistic. I've
found that all the memory is allocated in this stack:

Allocated 17673781248 bytes in 556 allocations
        cds_lfht_alloc_bucket_table3     from liburcu-cds.so.2.0.0
        _do_cds_lfht_resize      from liburcu-cds.so.2.0.0
        do_resize_cb             from liburcu-cds.so.2.0.0
        call_rcu_thread          from liburcu-qsbr.so.2.0.0
        start_thread             from libpthread-2.12.so
        clone                    from libc-2.12.so

According pstack it should be quiescent state.  Call thread waits on syscall:
syscall
call_rcu_thread
start_thread
clone

We use urcu-0.8.7, only rculfhash (QSBR). Is it some kind of leak in
RCU or any chance I misuse it? What would you recommend to
troubleshoot the situation?


P.S. sorry if this email received multiple times: I'tried twice from
my work email and after few hours didn't notice the email in the list.