On Thu, Jul 11, 2019 at 11:41 PM Nitish Saboo <nitish.sabo...@gmail.com> wrote:
>
> syslogparser.go
> =============
>
> func (obj SyslogParser) LoadPatternDB(opts Syslog, workerId int) {
> patterndbpath := C.CString(opts.Patterndb) . <<<<<<<<<<<<<<< . STEP 1
> defer C.free(unsafe.Pointer(patterndbpath)) . <<<<<<<<<<<<<<<< STEP 2
> InitStruct := (*C.Accumulatedparams)(C.calloc(1,
> C.sizeof_struct_Accumulatedparams))
> InitStruct.callback = (C.key_value_cb)(C.callback)
> InitStruct.data = C.int(workerId)
> C.load_pattern_db(patterndbpath,
> (*C.Accumulatedparams)(unsafe.Pointer(InitStruct)), C.int(workerId))
> }
>
> Since I am running this program in multiple go routines, when we do above
> STEP 1 :
>
> 1)Will the C memory allocate different addresses for 'patterndbpath' in both
> the routines ...Am I right ?
Yes.
> 2)You said 'It may be calling free twice on the same pointer', but I am
> assigning a different pointer in STEP 1 everytime for each routine...Am I
> right ?
Yes, you will see a different pointer each time you call C.calloc, and
in the code that I see that pointer is only freed once, but I have no
idea what the rest of your code is doing.
> 3)Is it possible that one Go routine has already freed up the address that
> the other Go routine is trying to free and that is causing this 'fatal
> error: bin/main': double free or corruption (fasttop)'
Yes, that is possible. It won't happen with the code I see above but
I have no idea what the rest of your code is doing.
> Is this because of the race condition between two routines that this error is
> seen ?
It is possible.
> 4)If you show us a small, complete, self-contained example, that does not
> call any other code, then we may be able to see the problem.
> >> As you have mentioned problem is happening when we call 'C.free'.Do you
> >> mean by not calling internal syslog-ng methods and just calling a normal C
> >> program with multiple go routines ?
> Please correct me here if I am wrong
I mean any small, self-contained example where we can see all the code.
You seem to be looking at a memory corruption or double free problem.
These are normal, ordinary, problems when writing C code. We can't
debug your problem for you.
Ian
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