Why does enabling concurrent builds slow single agent builds

Grant Huddlestone September 6, 2017

I have a Bamboo Standard: Commercial Server license.

When enabling concurrent builds in Administration > Plans > Concurrent builds all my plans, including those with a single stage containing a single job double in build time.

Additionally, stages with multiple jobs are built sequentially, and not in parallel amongst available qualifying agents. 

I've poured over the config but I must be missing something.

2 answers

0 votes
Grant Huddlestone September 7, 2017

Will do, Thanks

0 votes
Christian Glockner
Atlassian Team
Atlassian Team members are employees working across the company in a wide variety of roles.
September 6, 2017

Hi Grant,

Enabling concurrent builds will allow you to run another build of a plan, even if a previous build of the plan is still running - is that something that you're actually seeing? As with all builds, each of the concurrent builds will consume as many build agents as are required (and avaiable) to execute it

How many agents do you have available in total?

Cheers,

Christian

Premier Support Engineer

Atlassian

Grant Huddlestone September 6, 2017

Here's an example:

I have a test plan that contains two stages ('Build Artefacts' and 'Tests').

The 'Build Artefacts' stages contains one job ('build').

The 'Tests' stage contains 4 jobs ('bbox-all', 'bbox-c', 'unit' and 'wbox').

I kick of the build and the first stage completes successfully.

The build moves to the 'Tests' stage but does not attempt to run the 4 jobs in parallel. They are performed sequentially.

Seperately to this problem - when I enable concurrent builds my build time for ANY build doubles. When I deactivate it the build speed halves. This slowdown occurs even when only one build is running.

I have 4 qualifying agents for the test plan discussed above, and a total of 10 configured agents.

Thanks

Grant

Christian Glockner
Atlassian Team
Atlassian Team members are employees working across the company in a wide variety of roles.
September 6, 2017

Hi Grant,

Thanks for the detailed description!

While the jobs are executing in sequence, what's the status of all agents? Are they all engaged or are some of them idle and able to execute these jobs?

Cheers,

Christian

Premier Support Engineer

Atlassian

Grant Huddlestone September 7, 2017

Hi Christian,

The remaining qualifying agents are all idle and theoretically able to be used.

Kind regards

Grant

Christian Glockner
Atlassian Team
Atlassian Team members are employees working across the company in a wide variety of roles.
September 7, 2017

Hi Grant,

That's all very surprising, so I think we need to dig deeper and go through the logs to get a better idea of what's going on.

Since you have a commercial license you should have access to support, so I suggest you create a ticket at support.atlassian.com and attach a support zip from Bamboo to start with so we can take it from there.

Cheers,

Christian

Premier Support Engineer

Atlassian

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