[TS-4840] Crash when reattaching to C++ API Stats.

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 7.0.0
• Fix Version/s: 7.1.0
• Component/s: CPP API, Metrics
• Assignee: James Peach
• Reporter: James Peach
• Created: 09/Sep/16 20:03
• Updated: 09/Nov/16 18:35
• Resolved: 09/Nov/16 18:35

Description

Program received signal SIGSEGV, Segmentation fault.
0x00000000007f733c in ink_atomic_swap<long> (mem=0x0, value=1) at ../../lib/ts/ink_atomic.h:76
76	  return __sync_lock_test_and_set(mem, value);
(gdb) where
#0  0x00000000007f733c in ink_atomic_swap<long> (mem=0x0, value=1) at ../../lib/ts/ink_atomic.h:76
#1  0x00000000007f6e56 in RecSetGlobalRawStatSum (rsb=0x2f16290, id=6, data=1) at RecRawStats.cc:482
#2  0x00000000005372c9 in TSStatIntSet (the_stat=6, value=1) at InkAPI.cc:6944
#3  0x00002ae6d3398bb1 in atscppapi::Stat::set (this=0x2ae6d37c2890 <...>, value=1) at Stat.cc:78
#4  0x00002ae6d35bb826 in TSPluginInit (argc=1, argv=0x7ffd0613bfe0) at /home/jpeach/n/....cc:753
#5  0x00000000005550e5 in plugin_load (argc=1, argv=0x7ffd0613bfe0, validateOnly=false) at Plugin.cc:137

The change in TS-4793 regressed the C++ API Stat object. What happens is that if you restart traffic_server without traffic_manager, the TSStatFindName call finds the metric in the records hash table, but traffic_server has not set up the RSB entry so actually incrementing it crashes.

If you call TSStatCreate twice for the same metric, you will end up with multiple RSB slots being consumed which is almost as bad.

Issue Links

• links to: GitHub Pull Request #1012