Scripted Pipeline supports nested parallel steps at the execution level, although visualizations like Blue Ocean only support one level of parallelization, and Declarative Pipeline does not natively support nested parallel, and I do not think nested parallel has much real-world use or testing. Also, there have been some subtle bugs related to Pipeline durability with nested parallel steps in the past, so you may want to do some related testing with your Pipeline before committing to nested parallel if durability is important to you.
Thanks, Devin On Tuesday, November 2, 2021 at 12:42:14 AM UTC-4 abstrakta wrote: > So nested parallel is allowed too ? > ---Original--- > *From:* "'Devin Nusbaum' via Jenkins Users"<jenkins...@googlegroups.com> > *Date:* Mon, Nov 1, 2021 21:27 PM > *To:* "jenkinsci-users"<jenkins...@googlegroups.com>; > *Subject:* Re: thread safety of scripted pipeline parallel and usage of > nested parallel > > The Pipeline execution engine uses a "green thread" model internally - > there is only ever one Java thread executing the Groovy DSL for a given > Pipeline (step execution may use additional Java threads, but this should > always be transparent to users). See the final paragraph under > https://github.com/jenkinsci/workflow-cps-plugin#technical-design for a > few more details. You should not need to worry about Java thread safety > across the various branches in a parallel step as long as you are not doing > anything with Java threads directly in your Pipeline. > > On Mon, Nov 1, 2021 at 7:03 AM kuisathaverat <kuisat...@gmail.com> wrote: > >> Jenkins pipelines have two types of code, the steps and directives >> provided by Jenkins, and the Groovy code. >> All the Jenkins steps and directives are thread safe. On your Groovy you >> must guarantee is thread-safe if it needs to be. >> Unstash and archive are Jenkins steps you can use them in parallel tasks >> and they must work as expected, I only see one case that archive can cause >> issues and is when you archive the same artifact name from different tasks, >> but is completely logical that fails or corrupt the file due to you ar >> doing something wrong (the same happens with stash in parallel tasks) >> The last thought, try to minimize all the groovy code you add to your >> pipelines, all Groovy code run in the Jenkins controller, try to delegate >> on scripts, commands, tools, ... as much as possible. >> >> El dom, 31 oct 2021 a las 18:55, 'abstrakta' via Jenkins Users (< >> jenkins...@googlegroups.com>) escribió: >> >>> sorry, pipeline code should be correct like this: >>> pipeline { >>> agent any >>> stages { >>> stage('Parallel Build') { >>> steps { >>> script { >>> def builds = [:] >>> def tests = [:] >>> stash name: 'src', include: 'src/**' >>> >>> def build_action = { platform, tests -> >>> >>> //build in some slave node. >>> node ("${platform}") { >>> //unstash need thread mutex lock? >>> unstash name: 'src' >>> >>> sh "make ${platform}" >>> >>> //archive need thread mutex lock? >>> archive name: "./${platform}" >>> } >>> >>> //nested parallel, outside of node block >>> parallel tests >>> } >>> >>> def test_action = { platform -> >>> //test in some slave node. >>> node ("${platform}") { >>> sh "make ${platform}-test" >>> } >>> } >>> >>> tests["A1"] = { test_action("A1") } >>> tests["A2"] = { test_action("A2") } >>> tests["A3"] = { test_action("A3") } >>> builds["A"] = { build_action("A",tests) } >>> >>> tests = [:] >>> tests["B1"] = { test_action("B1") } >>> tests["B2"] = { test_action("B2") } >>> builds["B"] = { build_action("B",tests) } >>> >>> tests = [:] >>> tests["C1"] = { test_action("C1") } >>> tests["C2"] = { test_action("C2") } >>> builds["C"] = { build_action("B",tests) } >>> >>> parallel builds >>> } >>> } >>> } >>> } >>> } >>> >>> ---原始邮件--- >>> *发件人:* "'abstrakta' via Jenkins Users"<jenkins...@googlegroups.com> >>> *发送时间:* 2021年10月31日(周日) 晚上10:48 >>> *收件人:* "jenkinsci-users"<jenkins...@googlegroups.com>; >>> *主题:* 回复： thread safety of scripted pipeline parallel and usage of >>> nested parallel >>> >>> OK,I know what you means. But I test these pipeline that data is not >>> synchronized many times( about more than 700 times,I use periodical build >>> to test it automatically). Shared data that is not synchronized is >>> processed correctly every time. Do you really encounter the situation that >>> shared data is corrupt in parallel task? >>> >>> In some scenarios, I want to parallel build one more artifacts that used >>> in different platforms from the same source code. And then I parallel test >>> all artifacts in their corresponding platforms(One artifact might be used >>> in one more platforms). >>> >>> build platform: A B C >>> test platform: A(A1 A2 A3), B(B1 B2), C(C1 C2) >>> >>> -> A1 >>> -> A -> A2 >>> | -> A3 >>> / >>> source code --> B -> B1 >>> \ -> B2 >>> | >>> -> C -> C1 >>> -> C2 >>> -> C3 >>> >>> Pipeline code like this: >>> >>> pipeline { >>> agent any >>> stages { >>> stage('Parallel Build') { >>> steps { >>> script { >>> def builds = [:] >>> def tests = [:] >>> stash name: 'src', include: 'src/**' >>> >>> def build_action = { platform, tests -> >>> >>> //build in some slave node. >>> node ("${platform}") { >>> //unstash need thread mutex lock? >>> unstash name: 'src' >>> >>> sh "make ${platform}" >>> >>> //archive need thread mutex lock? >>> archive name: "./${platform}" >>> } >>> >>> //nested parallel, outside of node block >>> parallel tests >>> } >>> >>> def test_action = { platform -> >>> //test in some slave node. >>> node ("${platform}") { >>> sh "make ${platform}-test" >>> } >>> } >>> >>> tests["A1"] = test_action("A1") >>> tests["A2"] = test_action("A2") >>> tests["A3"] = test_action("A3") >>> builds["A"] = build_action("A",tests) >>> >>> tests = [:] >>> tests["B1"] = test_action("B1") >>> tests["B2"] = test_action("B2") >>> builds["B"] = build_action("B",tests) >>> >>> tests = [:] >>> tests["C1"] = test_action("C1") >>> tests["C2"] = test_action("C2") >>> builds["C"] = build_action("B",tests) >>> >>> parallel builds >>> } >>> } >>> } >>> } >>> } >>> >>> I have been running this pipeline for some time. It works well. But I >>> worry about the thread safety of unstash(and archive，or other commands). I >>> want to find some evidence that Jenkins garantee these parallel thread >>> safety and nested parallel is ok. Otherwise I must split these platforms >>> into different build jobs(which I think it's more difficult to manage >>> projects.) Because Jenkins must garantee parallel build jobs more safe? I >>> just don't know the underlying works that Jenkins do about parallel.I'm >>> just curious about these thread safety.If Jenkins take care of these >>> synchronization,that is the best. If such, I don't need to care about these >>> thread things. If not,I want to find correct ways to do parallel tasks. >>> >>> ------------------ 原始邮件 ------------------ >>> *发件人:* "jenkinsci-users" <kuisat...@gmail.com>; >>> *发送时间:* 2021年10月31日(星期天) 晚上7:19 >>> *收件人:* "Jenkins Users"<jenkins...@googlegroups.com>; >>> *主题:* Re: thread safety of scripted pipeline parallel and usage of >>> nested parallel >>> >>> The following example should work (I did not test it), I my case I have >>> used maps like the “result” variable, that it is a simple map not >>> synchronized and stores data from all task but it is not read from the >>> different tasks. The other two cases “data” and “mapSync” uses concurrent >>> classes, they are thread safe and synchronized so you can share data across >>> tasks, I dunno is they are in the allow list for pipeline, if not you have >>> to approve it use in pipelines in the Jenkins config. Finally, the last >>> part of the pipeline uses nested parallel task, from my experience is not a >>> good idea, the parallel explosion of task is a little incontrolable and >>> there are other solution like launch a job from those task and inside that >>> job launch parallel task, in this way you only have 1 parallel level that >>> is easy to control and understand when something goes wrong. >>> >>> import groovy.transform.Field >>> import java.util.concurrent.atomic.AtomicInteger >>> import java.util.concurrent.ConcurrentHashMap >>> >>> @Field def results = [:] >>> @Field AtomicInteger data = new AtomicInteger() >>> @Filed ConcurrentHashMap mapSync = new >>> ConcurrentHashMap<String,Integer>() >>> >>> pipeline{ >>> agent any >>> stages >>> { >>> stage(‘Parallel BuiLd’) { >>> steps { >>> script { >>> def i = 0 >>> def builds = [:] >>> mapSync[“odd”] = 0 >>> mapSync[“even”] = 0 >>> stash name: ‘src’, include: ‘src/**’ >>> //generate 1000 parallel block >>> for (i = 0; i<1000; i++) { >>> // make the Map of Closure >>> builds[“$i”] = { >>> results[“$i”] = 1 >>> data++ >>> if(i%2==0){ >>> mapSync[“odd”] = mapSync[“odd”]++ >>> } else { >>> mapSync[“even”] = mapSync[“even”]++ >>> } >>> } >>> } >>> parallel builds >>> println results.toString() >>> println data >>> println mapSync >>> } >>> } >>> } >>> } >>> } >>> El sábado, 30 de octubre de 2021 a las 18:44:57 UTC+2, abstrakta >>> escribió: >>> >>>> Thanks for your reply. >>>> So parallel directive is like spawning some Java threads?Do you have >>>> any pipeline code can demo this thread safety issue and how to fix it >>>> using >>>> Java types that are thread safe ? >>>> I guess that some directive "stash unstash archive" should be thread >>>> safety internally.Because I find some articles use parallel unstash in >>>> different slave node without thread protection.Is my guess correct?I can't >>>> find any other articles that discuss this parallel thread safety issue. >>>> ---Original--- >>>> *From:* "Ivan Fernandez Calvo"<kuisat...@gmail.com> >>>> *Date:* Sun, Oct 31, 2021 00:03 AM >>>> *To:* "Jenkins Users"<jenkins...@googlegroups.com>; >>>> *Subject:* Re: thread safety of scripted pipeline parallel and usage >>>> of nested parallel >>>> >>>> No, if you plan to use shared variables across parallel steps you >>>> should use Java types that are thread safe, if not you will have >>>> random/weird results. I have several pipelines that uses a map to store >>>> results in parallel steps >>>> >>>> El sábado, 30 de octubre de 2021 a las 14:18:29 UTC+2, abstrakta >>>> escribió: >>>> >>>>> Hi, Jenkins friends.I wish that I'm in the right place that post these >>>>> Jenkins usage question. >>>>> >>>>> I find that the Scriped Pipeline parallel works like threads.Unlike >>>>> the Declarative Pipeline parallel,the Scriped Pipeline parallel just use >>>>> one executor.Closure in parallel parameters works like a thread. >>>>> My question is: >>>>> >>>>> 1.Does Jenkins garantee the data thread safety of parallel closure >>>>> internally? >>>>> >>>>> 2.Does I need to care about the thread safety of the commands that >>>>> executes in scriped parallel closure? >>>>> >>>>> 3.Is there any limit of usage in the commands that executes in >>>>> parallel?Can I use nested scripted parallel? Why the documentation of >>>>> Declarative Pipeline parallel in Pipeline Syntax reference says that >>>>> "Note >>>>> that a stage must have one and only one of steps, stages, parallel, or >>>>> matrix. It is not possible to nest a parallel or matrix block within a >>>>> stage directive if that stage directive is nested within a parallel or >>>>> matrix block itself." >>>>> >>>>> I test some nested Pipeline code that might cause thread race >>>>> condition many times.Jekins always give the right answer that shared data >>>>> is modified correctly.Is this thread safety garanteed in the design of >>>>> Jenkins parallel directive? >>>>> >>>>> Pipeline code like this: >>>>> >>>>> pipeline{ >>>>> agent any >>>>> stages >>>>> { >>>>> stage('Parallel BuiLd') { >>>>> steps { >>>>> script { >>>>> def i = 0 >>>>> def data = 0 >>>>> def builds = [:] >>>>> stash name: 'src', include: 'src/**' >>>>> //generate 1000 parallel block >>>>> for (i = 0; i<1000; i++) { >>>>> // make the Map of Closure >>>>> builds["$i"] = { >>>>> //modify shared data, need thread mutex >>>>> lock? >>>>> data++ >>>>> //unstash or other command, need thread >>>>> mutex lock? >>>>> unstah name: 'src' >>>>> def tests = [:] >>>>> // ... generate tests Map >>>>> // Can I use nested parallel? >>>>> parallel tests >>>>> } >>>>> } >>>>> parallel builds >>>>> println data //It does always print 1000 >>>>> } >>>>> } >>>>> } >>>>> } >>>>> } >>>>> >>>>> The variable data is always modified to 1000. So Jenkins garantee the >>>>> thread safety of parallel? >>>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Jenkins Users" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to jenkinsci-use...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/jenkinsci-users/0712b8c5-42dc-439f-a017-2a5ca45ad1e9n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/jenkinsci-users/0712b8c5-42dc-439f-a017-2a5ca45ad1e9n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Jenkins Users" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to jenkinsci-use...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/jenkinsci-users/fed01b0e-a04c-448b-9f32-3d2b3ffd6c40n%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/jenkinsci-users/fed01b0e-a04c-448b-9f32-3d2b3ffd6c40n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Jenkins Users" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to jenkinsci-use...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/jenkinsci-users/tencent_579508DE2429C25B92D7BFFF6AED09115C08%40qq.com >>> >>> <https://groups.google.com/d/msgid/jenkinsci-users/tencent_579508DE2429C25B92D7BFFF6AED09115C08%40qq.com?utm_medium=email&utm_source=footer> >>> . >>> >>> -- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "Jenkins Users" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/jenkinsci-users/9fzFnwLkfxU/unsubscribe >>> . >>> To unsubscribe from this group and all its topics, send an email to >>> jenkinsci-use...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/jenkinsci-users/tencent_E81808632457C23792EEBFC46A5A093E5C08%40qq.com >>> >>> <https://groups.google.com/d/msgid/jenkinsci-users/tencent_E81808632457C23792EEBFC46A5A093E5C08%40qq.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> >> -- >> Un Saludo >> Iván Fernández Calvo >> https://www.linkedin.com/in/iv%C3%A1n-fern%C3%A1ndez-calvo-21425033 >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Jenkins Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to jenkinsci-use...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/jenkinsci-users/CAKo5Qrq%2BP9qYn%3Dm9Ssc4aSCAkedr_7D1jRTSuKYPQNxJ_3xrmw%40mail.gmail.com >> >> <https://groups.google.com/d/msgid/jenkinsci-users/CAKo5Qrq%2BP9qYn%3Dm9Ssc4aSCAkedr_7D1jRTSuKYPQNxJ_3xrmw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "Jenkins Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to jenkinsci-use...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/jenkinsci-users/CAF73ShC883ws%3DYvMVcBeeR%3Dyub8iyjA0%3DidL_pzDocki0Rp5dg%40mail.gmail.com > > <https://groups.google.com/d/msgid/jenkinsci-users/CAF73ShC883ws%3DYvMVcBeeR%3Dyub8iyjA0%3DidL_pzDocki0Rp5dg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Jenkins Users" group. 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