remoting has tons of improvements between those two versions 3.33 vs 4.5, 
if you agents ar JNLP the new default protocols is JNLP 4 that is it's 
better than JNLP 3 IIRC it has an important performance issue 

El jueves, 1 de octubre de 2020 a las 12:33:53 UTC+2, Dominik escribió:

> We upgraded our Jenkins instance yesterday (from version 2.190.1 to 
> 2.249.1) and the heavy load on the master "magically disappeared".
> The exact same test suite now runs (and 'spams' all the agents), but the 
> load on master stays below a value of 3 (with 4 CPUs).
>
> On Friday, September 25, 2020 at 5:05:11 PM UTC+2 Dominik wrote:
>
>> Hi Kamil,
>>
>> Thanks for the link. Although we do use pipelines for many projects, the 
>> set of test jobs I mentioned are plain old 'freestyle' jobs.
>> They include one or multiple Maven build steps which run some more or 
>> less heavy unit and integration tests (which all happens on agents anyway).
>> When looking at top/htop on the server during those tests, it's really 
>> just the Jenkins main process rotating at 380-400% CPU usage (of 4 CPUs).
>>
>> Regards,
>> Dominik
>>
>> On Friday, September 25, 2020 at 3:28:23 PM UTC+2 [email protected] 
>> wrote:
>>
>>> Hi Dominik,
>>>
>>> High load on the master might be caused by incorrectly implemented 
>>> Jenkinsfiles which contain complex logic, thus inducing load on the master 
>>> instead of the nodes. Furthermore, this load will not be visible in the 
>>> node overview. I think this is the best point to start investigating this 
>>> issue from, see this piece of documentation for explanation: 
>>> https://www.jenkins.io/doc/book/pipeline/pipeline-best-practices/#making-sure-to-use-groovy-code-in-pipelines-as-glue
>>>
>>> Best regards,
>>> Kamil
>>>
>>> On Friday, September 25, 2020 at 2:26:47 PM UTC+2 Dominik wrote:
>>>
>>>> Hi,
>>>>
>>>> We are running Jenkins with about 20 build agents on separate VMs (with 
>>>> up to 4 executors each). The master has 4 CPUs, so I would expect a load 
>>>> of 
>>>> about 4 when there's "a lot of work" to be done.
>>>>
>>>> However, no job is ever scheduled on the master itself, and still we 
>>>> can observe very high load levels on the master when many jobs are running 
>>>> concurrently on the agents. For example, one of our test suites launches 
>>>> about 30 jobs (lasting 5-20min each) in a 1h time slot and at that moment 
>>>> the master reaches a load of up to 40, with all CPUs fully occupied! 
>>>> However, looking at the UI, all jobs clearly run on the agents, and the 
>>>> master simply shows as 'Idle'.
>>>>
>>>> When I look at Jenkins' own monitoring, I see a huge amount of 
>>>> *Computer.threadPoolForRemoting 
>>>> *and similar threads with a summary stating *Threads on master: *Number 
>>>> = 415, Maximum = 511, Total started = 7,731,717.
>>>>
>>>> Can anyone give some insight on what could be going on? What can be the 
>>>> reasons for high load on the master when all the jobs are running on 
>>>> agents?
>>>>
>>>> Regards,
>>>> Dominik
>>>>
>>>

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