[tor-relays] Tor RAM usage (DoS or memory leaks?)

[Roman Mamedov]

Hello,

There seems to be an issue with Tor's memory usage.
Earlier today, with Tor 3.5.7 and 1.5 GB of RAM running two Tor processes, the
machine got 430 MB into swap, slowing down to a crawl from iowait on accessing
the swapped out memory. Typically 1.5 GB is more than enough for these. "VIRT"
in top was ~1GB each, and "RES" was ~512MB each. Which is weird because that
doesn't add up to exhausting the 1.5 GB, and there are no other heavy
processes on the machine running. I rebooted it without further investigation. 

And right now on another machine running 2.9.16 I see:

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
22432 debian-+  30  10 5806816 5.157g  10464 R  39.5 33.1  39464:19 tor 

But not sure if it just accumulated 5.1GB of RAM slowly over time, or shot up
recently.

Feb 01 17:00:49.000 [notice] Heartbeat: Tor's uptime is 82 days 23:59 hours,
with 70705 circuits open. I've sent 66622.45 GB and received 65906.91 GB.
Feb 01 17:00:49.000 [notice] Circuit handshake stats since last time:
11361/11361 TAP, 239752/239752 NTor.
Feb 01 17:00:49.000 [notice] Since startup, we have initiated 0 v1
connections, 0 v2 connections, 10 v3 connections, and 3385644 v4 connections;
and received 14 v1 connections, 78592 v2 connections, 822108 v3 connections,
and 8779474 v4 connections.
Feb 01 17:00:49.000 [notice] DoS mitigation since startup: 2899572 circuits
rejected, 121 marked addresses. 561 connections closed. 21956 single hop clients refused.
Feb 01 17:08:20.000 [warn] connection_edge_process_relay_cell (at origin)
failed.

-- 
With respect,
Roman