Timeout for Parallel::ForkManager


At tonight's Chicago Perl Mongers Office Hours, Ray came up with an interesting problem. While testing all of CPAN for CPAN Testers, how do you detect when a test is hanging and kill it before it takes down the entire machine? How do you simply kill a test that is taking too long? And how do you do it without having a wholly separate watchdog program?

Ray's using Parallel::ForkManager to execute testing jobs in parallel across multiple Perl installs. There are a few ways we could implement timeouts, including IPC::Run's timeout function, or the alarm Perl built-in, but these must all be implemented in the child process. It'd be nicer if we could use the parent process to watch its own children.

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Choosing a Log Level


Like all subjective decisions in technology, which log level to use is the cause of much angry debate. Worse, different logging systems use different levels: Log4j has 6 severity levels, and Syslog has 8 severity levels. While both lists of log levels come with guidance as to which level to use when, there's still enough ambiguity to cause confusion.

When choosing a log level, it's important to know how visible you want the message to be, how big of a problem it is, and what you want the user to do about it. With that in mind, this is the decision tree I follow when choosing a log level:

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CPAN Testers Has a New API


As part of the MetaCPAN hackathon, meta::hack, I was invited to work on the CPAN Testers integration. CPAN Testers is a community of CPAN users who send in test reports for CPAN modules as they are uploaded. MetaCPAN adds a summary of those test reports to every CPAN distribution to help you determine which module you'd most like to use. For quite a few months, this integration was broken, and the nature of the current integration (a SQLite database) means it is not as generally useful as it could be.

So, I decided that the best way to improve the CPAN Testers / MetaCPAN integration was to build a new CPAN Testers API. This API uses the CPAN Testers schema to expose CPAN Testers data using a JSON API. This API is built using the Mojolicious web framework, and an OpenAPI specification (using Mojolicious::Plugin::OpenAPI.

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Yuletide Logging


'Twas a night before Christmas and on the ops floor
All the servers were humming behind the closed door
The app was deployed to the servers with care
In hopes that the customers soon would be there
When from out of the phone there arose such a clatter
I sprang out of my chair to see what was the matter
"The website is down!" said the boss with a shout
"We need to make money, so figure it out!"
I logged in to the server and looked all around
But the app had no logging; no reason was found
With no other choice, I called the developer
Who said "just restart it, I'm sure that'll fix 'er"
I ran the right service, up the app came
Only to come down again and again
If there but was a way to know what was wrong
I could fix it for sure, but no logging was found

Good logging is crucial for applications in production. In an emergency, you will want it to be as easy as possible to track down problems when they happen. With good logs you can ensure that minor bugs don't cause major downtime and data loss problems. Good logs can help track down security issues and can provide an auditable trail of changes to track down who did what and when.

Log::Any is a lightweight, generic API built for interoperable logging for CPAN modules. Much like DBI allows interoperable database interfaces, CHI allows interoperable caching interfaces, and PSGI allows interoperable web applications, Log::Any allows a CPAN module to produce logs that fit into your environment whether you just want to see logs on your terminal, you're using Log4perl to directly send e-mail alerts to your operations team, or you're using a local rsyslog daemon to transmit logs to an ElasticSearch instance via Logstash.

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