Re: [boost] [build] No output until an action completes?

Subject: Re: [boost] [build] No output until an action completes?
From: Vladimir Prus (vladimir.prus_at_[hidden])
Date: 2017-07-06 14:46:06

On 06/07/2017 16:40, Tom Westerhout via Boost wrote:
> Greetings!
>
>
> I've run into a problem that a Boost.Build action produces no output until
> the command returns.

Hi Tom,

that is correct. The motivation is that with parallel builds, producing 
output while a command is running results in interleaved output that
is quite impossible to understand. Therefore, the output is buffered,
and then written together when the action is finished.

> For example, in my Jamfile I have
> actions do-measure
> {
>     $(COMMAND) $(ARGS)
> }
>
> notfile ha : @do-measure : ... : ... ;
>
> COMMAND is a Python script that runs for a long time and produces some
> debug information. But b2 does not print this output until COMMAND
> returns. This is really unfortunate because Travis requires a command to
> produce output at least once per 10 mins or something. Otherwise it thinks
> the command has stalled and terminates it.

This is a valid use case for long running tasks. Could you file an issue?

- Volodya

>
> Is there some configuration parameter or a trick to make b2 print the
> debug info COMMAND produces? or maybe some dummy output so that Travis
> allows it to run longer than 10 mins?
>
> Any help is highly appreciated!
>
>
> Tom
>
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