CODEWITHSUNDEEP
csegmentation-faultgdb
manish ma
manish ma

Reputation: 2028

What can cause gdb to not stop on a breakpoint?

I placed a breakpoint on a function label in gdb. This breakpoint was hit multiple times, but this last time - it was missed and segmentation-fault occurred.

What could cause gdb to not stop on a breakpoint? Why didn't it stop on line 1018 this last time?

(gdb) b ambl_test_event_processor
Breakpoint 1 at 0x5852d6e0: file code/comn/ambl/ambltest.c, line 1018.
(gdb) c
Continuing.
[LWP 1139 exited]
[Switching to LWP 1148]

Thread 39 "Metaswitch_0_3" hit Breakpoint 1, ambl_test_event_processor (ambl_data=0x72f97b28, mib_data=0x7922b8f4, req_data=0x7280e784, row_cb=0x0, 
    rc=1, ambl_replication=0 '\000') at code/comn/ambl/ambltest.c:1018
1018    code/comn/ambl/ambltest.c: No such file or directory.
(gdb) c 
Continuing.
[Switching to LWP 1151]

Thread 42 "Metaswitch_0_6" hit Breakpoint 1, ambl_test_event_processor (ambl_data=0x72ff9508, mib_data=0x7932bda0, req_data=0x7280e71c, row_cb=0x0, 
    rc=1, ambl_replication=0 '\000') at code/comn/ambl/ambltest.c:1018
1018    in code/comn/ambl/ambltest.c
(gdb) c
Continuing.
[Switching to LWP 1145]

Thread 36 "Metaswitch_0_0" hit Breakpoint 1, ambl_test_event_processor (ambl_data=0x72efb544, mib_data=0x7280b4e4, req_data=0x7280e6e8, row_cb=0x0, 
    rc=1, ambl_replication=0 '\000') at code/comn/ambl/ambltest.c:1018
1018    in code/comn/ambl/ambltest.c
(gdb) c
Continuing.
[Switching to LWP 1150]

Thread 41 "Metaswitch_0_5" hit Breakpoint 1, ambl_test_event_processor (ambl_data=0x72ffbc8c, mib_data=0x79622694, req_data=0x7280e750, row_cb=0x0, 
    rc=1, ambl_replication=0 '\000') at code/comn/ambl/ambltest.c:1018
1018    in code/comn/ambl/ambltest.c
(gdb) 
Continuing.

Thread 42 "Metaswitch_0_6" received signal SIGSEGV, Segmentation fault.
[Switching to LWP 1151]
0x5852d996 in ambl_test_event_processor (ambl_data=0x0, mib_data=0x7932bda0, req_data=0x7280e71c, row_cb=<optimized out>, rc=<optimized out>, 
    ambl_replication=0 '\000') at code/comn/ambl/ambltest.c:1568
1568    in code/comn/ambl/ambltest.c

Upvotes: 0

Views: 146

Answers (1)

Employed Russian
Employed Russian

Reputation: 213375

What could cause gdb to not stop on a breakpoint? Why didn't it stop on line 1018 this last time?

You haven't shown any proof that it didn't.

You have:

Thread 42 "Metaswitch_0_6" hit Breakpoint 1
Thread 36 "Metaswitch_0_0" hit Breakpoint 1,
Thread 41 "Metaswitch_0_5" hit Breakpoint 1,
Thread 42 "Metaswitch_0_6" received signal SIGSEGV

There is no indication that thread 42 has finished running ambl_test_event_processor() after it hit the breakpoint, and then somehow skipped that breakpoint, then crashed.

More likely is that it hit the breakpoint (then some other threads also hit it, but that is irrelevant), then crashed.

Upvotes: 1

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