[erlang-questions] Lost messages

Attila Rajmund Nohl <>
Mon Jul 27 14:39:56 CEST 2009


The linking itself does not avoid the problem, it just makes it occur
less often (thus harder to reproduce in case it leads to a bug). If
the message is sent after the process died, but before the 'EXIT'
message is received (due to linking), it's still a problem.

By the way, an interesting race condition I've seen a couple of months ago:
process A links to process B, which in turn links to process C.
Process A also monitors process C and none of the processes trap
exits. What happens if process C gets (brutally) killed? The code I
was fixing was based on the assumption that process A receives the
{'DOWN', ...} message (because of the monitor), but in real life
process A was killed before the {'DOWN',...} message was received,
leading to a bug...

2009/7/27, Mazen Harake <>:
> Hi George,
>
> I'm curious in which situation you are considering this a problem. Can
> you please elaborate?
>
> Also, if you can, you should somehow link to the processes and clean
> them up from the ETS table to avoid this problem.
>
> Regards,
>
> /Mazen
>
> George Xu wrote:
>> It is said that send message is safe. But I count the problem of lost
>> message.
>>
>> The situation is like this:
>>
>> 1. I use a ets table to store all process to be communicated.
>> 2. But those process will terminated with some cases.
>> 3. In case of one process is terminated but still not reflected to the ets
>>
>> table, send message to this process happened sametimes. It seems the
>> message is send, but it can not reach since the process is termiated and
>> the message is lost.
>>
>> Anyone knows how to solve this problem?
>>
>> ━━━━━━━━━━━━━━━━━━━━━━━━━━
>> 徐翔 George Xu
>>
>> Mobile Internet Service Lab, Lonovo Corp. Research China
>> Tel:86-10-58866181
>> E-mail:
>> No.6 Shang Di West Road, Haidian District,
>> Beijing, 100085
>> P.R.China
>>
>
>
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>


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