[dancer-users] Problem with web service using dancer2
Stefan Hornburg (Racke)
racke at linuxia.de
Wed Feb 22 14:27:08 GMT 2017
On 02/22/2017 03:20 PM, Benjamins, John wrote:
> Hi,
>
> Sorry, you are right, it is actually using Dancer2::Plugin::Pg. Unfortunately I did not write this code, so I am not sure why it is checking $?, but that would seem to be a way to get unexpected results (which is what we are seeing!). What is the correct way to check the result of something like: $pg->selectAll( $query, $env_name )? How do I know the error returned, if any? Sorry if this is a basic question...
>
> Thank you again!
>
> John
Hello John,
this plugin uses DBI behind the scenes - so if you have set RaiseError: 1, it will cause a 500 if the query fails.
So checking $? is itself causing unexpected results. If you want to see if a query crashes, you can wrap the
selectall call in an eval and check $@ - that makes more sense.
Regards
Racke
>
> -----Original Message-----
> From: dancer-users [mailto:dancer-users-bounces at dancer.pm] On Behalf Of Stefan Hornburg (Racke)
> Sent: Wednesday, February 22, 2017 7:40 AM
> To: dancer-users at dancer.pm
> Subject: Re: [dancer-users] Problem with web service using dancer2
>
> On 02/22/2017 01:32 PM, Benjamins, John wrote:
>> Hi,
>>
>> The log has this for one of 20 threads with PID 37775:
>>
>> [37775] Read 366 bytes: "GET /v1/environments/testtest1/requests HTTP/1.1\r\nHost: apews:8096\r\nUser-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0\r\nAccept: application/json, text/javascript, */*; q=0.01\r\nAccept-Language: en-US,en;q=0.5\r\nAccept-Encoding: gzip, deflate\r\nReferer: http://apews:8080/ape_mgmt/\r\nOrigin: http://apews:8080\r\nConnection: keep-alive\r\n\r\n"
>> [EnvMgmt:37775] core @2017-02-22 02:17:09> looking for get
>> /v1/environments/testtest1/requests in
>> /usr/local/share/perl5/Dancer2/Core/App.pm l. 34 [EnvMgmt:37775] core
>> @2017-02-22 02:17:09> Entering hook core.app.before_request in (eval
>> 176) l. 1 [EnvMgmt:37775] info @2017-02-22 02:17:09> Sub: get_env_requests_status -- Query: select request_id AS requestnumber, client_code AS clientcode, request_status AS requeststatus, entity_id AS environment, request_url AS requesturl, request_method AS requestmethod, request_desc AS requestdesc, created_timestamp AS createdtime from entity_requests where entity_id = 'testtest1' in /home/dancer2/EnvMgmt/bin/../lib/EnvUtils.pm l. 240 [EnvMgmt:37775] info @2017-02-22 02:17:09> Sub: get_env_requests_status -- Exitcode: 72057594037927935 in /home/dancer2/EnvMgmt/bin/../lib/EnvUtils.pm l. 255 [EnvMgmt:37775] info @2017-02-22 02:17:09> ERROR: ARRAY(0x3e73f90) $VAR1 = [
>> { .... (data removed for brevity) ... }
>> ]; in /home/dancer2/EnvMgmt/bin/../lib/EnvUtils.pm l. 259
>> [EnvMgmt:37775] core @2017-02-22 02:17:09> Entering hook
>> core.app.after_request in (eval 176) l. 1 [37775] Wrote 285 bytes
>> [37775] Wrote 5 bytes [37775] Request done [37775] Waiting on previous
>> connection for keep-alive request...
>> [37775] Closing connection
>>
>> The code around l. 255 in EnvUtils.pm is:
>>
>> #
>> # Get requests status for selected environment.
>> #
>>
>> sub get_env_requests_status {
>> my ($env_name) = @_;
>>
>> # $env_name = $env_name . '%';
>>
>> my $pg = Pg;
>> my $debug = 'select request_id AS requestnumber,' .
>> ' client_code AS clientcode,' .
>> ' request_status AS requeststatus,' .
>> ' entity_id AS environment,' .
>> ' request_url AS requesturl,' .
>> ' request_method AS requestmethod,' .
>> ' request_desc AS requestdesc,' .
>> ' created_timestamp AS createdtime' .
>> ' from entity_requests' .
>> ' where entity_id = \'' . $env_name . '\'';
>> info "Sub: get_env_requests_status -- Query: $debug";
>>
>> my $query = 'select request_id AS requestnumber,' .
>> ' client_code AS clientcode,' .
>> ' request_status AS requeststatus,' .
>> ' entity_id AS environment,' .
>> ' request_url AS requesturl,' .
>> ' request_method AS requestmethod,' .
>> ' request_desc AS requestdesc,' .
>> ' created_timestamp AS createdtime' .
>> ' from entity_requests' .
>> ' where entity_id = ?';
>> my $result = $pg->selectAll( $query, $env_name );
>> my $exitcode = $? >> 8;
>>
>> info "Sub: get_env_requests_status -- Exitcode: $exitcode";
>>
>> if ($exitcode) {
>> my $str = sprintf("%s", Dumper($result));
>> info "ERROR: $result $str";
>> return 372; # Error: Cannot select the request status for selected env.
>> }
>>
>> return @{$result};
>> };
>>
>> And we are using Data::Dumper to print the $result of the query.
>>
>> Thank you!
>>
>> John
>
> Hello John,
>
> I thought you are using DBI ... but what kind of module is Pg?
>
> At any rate, it looks odd to me to query the exit code when you don't run an external command.
>
> Also I would use q{} or qq{} instead of appending lines with the dot operator.
>
> Regards
> Racke
>
>>
>> -----Original Message-----
>> From: dancer-users [mailto:dancer-users-bounces at dancer.pm] On Behalf
>> Of Stefan Hornburg (Racke)
>> Sent: Wednesday, February 22, 2017 7:03 AM
>> To: dancer-users at dancer.pm
>> Subject: Re: [dancer-users] Problem with web service using dancer2
>>
>> On 02/22/2017 12:56 PM, Benjamins, John wrote:
>>> Hi,
>>>
>>>
>>>
>>> We are using Dancer2 (version is 0.203001) to provide a web service, and this has been deployed in a Docker container.
>>> It is using Postgres as a database backend and perl DBI. We are
>>> having an issue were the service starts to return error
>>> 500 from database queries, even though it is returning what appears
>>> to be valid data. Any suggestions on where we should start looking?
>>> Restarting the pod running the web service fixes the issue for a while, but after a day or so of activity, the issue comes back.
>>>
>>>
>>>
>>> Please let me know if there is any additional information I can provide that would help describe the problem better.
>>>
>>>
>>>
>>> Thanks,
>>>
>>
>> Hello,
>>
>> what does Dancer report in the log file about the reason of the 500 error?
>>
>> Regards
>> Racke
>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>
>>
>> --
>> Ecommerce and Linux consulting + Perl and web application programming.
>> Debian and Sympa administration.
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>
>
> --
> Ecommerce and Linux consulting + Perl and web application programming.
> Debian and Sympa administration.
> _______________________________________________
> dancer-users mailing list
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> http://lists.preshweb.co.uk/mailman/listinfo/dancer-users
>
> This message is marked Public
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>
> Please consider the environment before printing this email and any attachments.
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Ecommerce and Linux consulting + Perl and web application programming.
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