[erlang-questions] Yaws process died when executing read_file

CGS <>
Wed Oct 19 15:57:39 CEST 2011


As far as I know, the only specific limitations in Erlang are related to 
the memory (if you impose this condition) and to the fact that you open 
your file to write as well (if I saw correctly, you opened the file as 
read_write). But, I am no expert in Erlang and maybe someone more 
knowledgeable can confirm or correct me here.

Nevertheless, it's good your problem was solved and I hope someone will 
satisfy your further curiosity (as I am in no position to do that due to 
my own limitation in knowledge on the subject). ;) :)

Cheers,
CGS




On 10/19/2011 03:44 PM, Martin Dimitrov wrote:
> Hi,
>
> No. The file is needed only by YAWS. But since YAWS doesn't cache it in
> memory, it tries to open it on every request and at some point the
> access error is returned. Windows 7 (the operating system we are testing
> on) has a very high limit of opened handles. Does Erlang have some
> limitation on this?
>
> Martin
>
> On 10/19/2011 3:54 PM, CGS wrote:
>> Hi,
>>
>> Well, that's a question I cannot answer (I can only give you wild
>> guesses), sorry. But if you need the file just with Erlang (not in
>> YAWS), why don't you use the same mechanism (meaning, passing the
>> buffer further and not accessing the harddisk all the time)? It seems
>> reasonable and faster than accessing it over and over from the harddisk.
>>
>> Cheers,
>> CGS
>>
>>
>>
>>
>> On 10/19/2011 02:36 PM, Martin Dimitrov wrote:
>>> Hello,
>>>
>>> Thanks for the reply.
>>>
>>> Looking through the config options I found max_size_cached_file which
>>> has a default value of 8 kb. The yaws file that is being requested is
>>> about 15 kb. Changing the option to 20 kb made the file cashed in memory
>>> and no errors are returned. But I wonder why erlang cannot open the file
>>> for reading.
>>>
>>> Thanks again.
>>>
>>> Martin
>>>
>>>
>>> On 10/19/2011 2:34 PM, CGS wrote:
>>>> Hi Martin,
>>>>
>>>> I suppose the access permission error is coming more from the number
>>>> of threads accessing that file and less from OS.
>>>>
>>>> Check your yaws.conf and override some default variables, especially
>>>> max_connections, keepalive_maxusers and process_options variables (or
>>>> fail_on_bind_err to check if it YAWS or external sources of
>>>> limitation). For more information look here:
>>>> http://yaws.hyber.org/yman.yaws?page=yaws.conf.
>>>>
>>>> Also, it wouldn't be such a bad idea to monitor your system resources
>>>> while setting up limits for connections.
>>>>
>>>> And the last thing, if you feel your hardware system is not used at
>>>> its maximum capacity, try running multiple YAWS systems.
>>>>
>>>> I hope it will help.
>>>>
>>>> Cheers,
>>>> CGS
>>>>
>>>>
>>>> On 10/19/2011 12:46 PM, Martin Dimitrov wrote:
>>>>> I do performance testing of our Erlang application with OpenSTA. The
>>>>> test runs with 300 virtual users. At some point the following errors
>>>>> start popping up:
>>>>>
>>>>> Yaws process died: {{badmatch,{error,eacces}},
>>>>>                    [{yaws_server,ut_read,1},
>>>>>                     {yaws_server,deliver_dyn_file,5},
>>>>>                     {yaws_server,aloop,3},
>>>>>                     {yaws_server,acceptor0,2},
>>>>>                     {proc_lib,init_p_do_apply,3}]}
>>>>>
>>>>> The call file:read_file(UT#urltype.fullpath) crashes in function
>>>>> ut_read(UT). I recompiled the module and printed the context. The
>>>>> error
>>>>> is eacces and UT holds:
>>>>>
>>>>> {urltype,yaws,
>>>>>                              {file_info,14088,regular,read_write,
>>>>>                                  {{2011,9,13},{11,51,42}},
>>>>>                                  {{2011,10,17},{17,59,44}},
>>>>>                                  {{2011,3,16},{13,18,58}},
>>>>>                                  33206,1,3,0,0,0,0},
>>>>>                              "/handler.yaws",
>>>>>
>>>>> "c:/Temp/harmony/script/../www/handler.yaws",
>>>>>                              "/",undefined,undefined,"text/html",
>>>>>                              "/handler.yaws",undefined}
>>>>>
>>>>> The file handler.yaws is the entry point of our app and is called on
>>>>> every request. When I run the test with 100 or less virtual users I
>>>>> don't see these errors. So how can it be "Missing permission for
>>>>> reading
>>>>> the file, or for searching one of the parent directories" as the error
>>>>> is described in the file:read_file documentation?
>>>>>
>>>>> Thanks in advance.
>>>>>
>>>>> Martin
>>>>> _______________________________________________
>>>>> erlang-questions mailing list
>>>>> 
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