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https://issues.apache.org/jira/browse/TS-2193?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13878995#comment-13878995
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Leif Hedstrom commented on TS-2193:
-----------------------------------
Cool, thanks for the update.
Btw, note that even without dedicated DNS thread, ATS will perform many
concurrent DNS lookups. The only difference is that you share DNS lookup with
the first "worker thread". By default, ATS allows up to 2048 concurrent DNS
lookups, but it's configurable:
{code}
CONFIG proxy.config.dns.max_dns_in_flight INT 2048
{code}
This is all done using asynchronous DNS lookups, so unless your first worker
thread (ET_NET 0) gets noticeably slammed, it shouldn't cause a lot of problem.
The dedicated DNS thread was created such that systems with a lot of DNS
lookups does not get lopsided load on the first worker thread.
> Trafficserver 4.1 Crash with proxy.config.dns.dedicated_thread = 1
> ------------------------------------------------------------------
>
> Key: TS-2193
> URL: https://issues.apache.org/jira/browse/TS-2193
> Project: Traffic Server
> Issue Type: Bug
> Components: DNS
> Affects Versions: 4.1.2
> Reporter: Tommy Lee
> Labels: Crash
> Fix For: 5.0.0
>
> Attachments: bt-01.txt
>
>
> Hi all,
> I've tried to enable DNS Thread without luck.
> When i set proxy.config.dns.dedicated_thread to 1, it crashes with the
> information below.
> The ATS is working in Forward Proxy mode.
> Thanks in advance.
> --------------------------------------
> traffic.out
> NOTE: Traffic Server received Sig 11: Segmentation fault
> /usr/local/cache-4.1/bin/traffic_server - STACK TRACE:
> /lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x2af714875cb0]
> /usr/local/cache-4.1/bin/traffic_server(_Z16_acquire_sessionP13SessionBucketPK8sockaddrR7INK_MD5P6HttpSM+0x52)[0x51dac2]
> /usr/local/cache-4.1/bin/traffic_server(_ZN18HttpSessionManager15acquire_sessionEP12ContinuationPK8sockaddrPKcP17HttpClientSessionP6HttpSM+0x3d1)[0x51e0f1]
> /usr/local/cache-4.1/bin/traffic_server(_ZN6HttpSM19do_http_server_openEb+0x30c)[0x53644c]
> /usr/local/cache-4.1/bin/traffic_server(_ZN6HttpSM14set_next_stateEv+0x6a0)[0x537560]
> /usr/local/cache-4.1/bin/traffic_server(_ZN6HttpSM14set_next_stateEv+0x57e)[0x53743e]
> /usr/local/cache-4.1/bin/traffic_server(_ZN6HttpSM14set_next_stateEv+0x57e)[0x53743e]
> /usr/local/cache-4.1/bin/traffic_server(_ZN6HttpSM27state_hostdb_reverse_lookupEiPv+0xb9)[0x526b99]
> /usr/local/cache-4.1/bin/traffic_server(_ZN6HttpSM12main_handlerEiPv+0xd8)[0x531be8]
> /usr/local/cache-4.1/bin/traffic_server[0x5d7c8a]
> /usr/local/cache-4.1/bin/traffic_server(_ZN18HostDBContinuation8dnsEventEiP7HostEnt+0x821)[0x5decd1]
> /usr/local/cache-4.1/bin/traffic_server(_ZN8DNSEntry9postEventEiP5Event+0x44)[0x5f7a94]
> /usr/local/cache-4.1/bin/traffic_server[0x5fd382]
> /usr/local/cache-4.1/bin/traffic_server(_ZN10DNSHandler8recv_dnsEiP5Event+0x852)[0x5fee72]
> /usr/local/cache-4.1/bin/traffic_server(_ZN10DNSHandler9mainEventEiP5Event+0x14)[0x5ffd94]
> /usr/local/cache-4.1/bin/traffic_server(_ZN7EThread13process_eventEP5Eventi+0x91)[0x6b2a41]
> /usr/local/cache-4.1/bin/traffic_server(_ZN7EThread7executeEv+0x514)[0x6b3534]
> /usr/local/cache-4.1/bin/traffic_server[0x6b17ea]
> /lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x2af71486de9a]
> /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x2af71558dccd]
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