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Re: [cu-dev] Behavior of virtual=true on Java SE 17
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Before, I assumed that the TCK verifies that virtual threads are used with virtual=true. But if it’s the case that even on Java 21 using virtual threads is optional, why we need a different behavior for Java 17?
What about just these 2 rules:
virtual=false, JDK 17 or 21 - Expect a platform thread
virtual=true, JDK 17 or 21 - Expect either a virtual or platform thread
On JDK 17, it would always be a platform thread. That also satisfies both expectations. Let’s not invent another special rule for Java 17 if the current rules for Java 21 work already for 17 too.
Ondro
Emily,
> I think now we are sort of agreeing on this
Incorrect, there has been no agreement on behavior and talk of the TCK has just derailed the discussion.
Whatever behavior we decide on we can test with the TCK one way or another (No tests have been delivered, only sample code written to prove testing is possible).
This is what has been decided:
virtual=false, JDK 21 - Expect a platform thread
virtual=true, JDK 21 - Expect either a virtual or platform thread
virtual=false, JDK 17 - Expect a platform thread
virtual=true, JDK 17 -
This is the only part of the matrix we haven't decided on:
- Should this be a runtime error?
- Should platforms ignore this and just return a platform thread?
- Should it be undefined (some products may choose to ignore, throw a runtime error, or fail to deploy the application)?
We can test any of these scenarios (including 3, which will be to not test anything, because there will be nothing to test, because it is undefined).
We really just need to vote on what we want and worry about the testing later since I have proven we can test any of these scenarios.
Thanks,
Kyle Jon Aure
I am pretty confused with the discussion.
I think now we are sort of agreeing on this: the VT TCK test should pass on both Java 17 and 21.
What kind of TCK are we talking about? We need to first clarify the precondition and postcondition on this.
My suggestion:
1. Precondition: set virtual=true
2. post condition: if Java 17, platform thread; If Java 21, virtual thread some times.
Now the question is how do we know the version of Java runtime is using, based on what Kyle said.
Correct, Steve.
I suggest that implementations decide whatever they want to do as long as they pass the TCK. And the TCK should make it possible to pass on Java 17, that's why I suggested that it doesn't verify that virtual threads are actually used. It's that simple. Let's do it and move on to something productive.
Ondro
On Wed, Feb 7, 2024 at 5:50 PM Steve Millidge (Payara) via cu-dev <
cu-dev@xxxxxxxxxxx> wrote:
OK was going on the comment in the email thread
“They should just ensure that an app with virtual=true can be deployed and runs as expected, regardless
of whether platform or virtual threads are used. Then the tests would pass both on Java 17 and 21.”
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Steve
Millidge
Founder & CEO
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From: Nathan Rauh <nathan.rauh@xxxxxxxxxx>
Sent: Wednesday, February 7, 2024 4:20 PM
To: Steve Millidge (Payara) <steve.millidge@xxxxxxxxxxx>; cu developer discussions <cu-dev@xxxxxxxxxxx>
Subject: Re: [cu-dev] Behavior of virtual=true on Java SE 17
Ondro will need to chime in to restate his position, but as I understand it from comments in the pull, it was to “leave it to implementations
how they react, whether they just ignore virtual=true and use platform threads, with or without a warning, or deployment fails.” I am trying to point out that this is
at odds with not skipping tests and skipping deployment of entire test applications because you don’t have any guarantee that the deployment will work if the vendor gets to choose.
The problem I see with skipping tests is that a vendor may not allow deployment of an application with virtual=true on 17 while
Ondo, I believe, was asserting that the application should deploy OK with virtual=true with 17 which is my preferred
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The problem I see with skipping tests is that a vendor may not allow deployment of an application with virtual=true on 17 while Ondo,
I believe, was asserting that the application should deploy OK with virtual=true with 17 which is my preferred option. My understanding (from memory) is that even on 21 this is a “hint” so the only thing you can really assert in the TCK regardless of the JDK
is that the task is ran in the way it would have ran previously before this “hint” existed.
It has never been in the plans for TCK tests to enforce that a virtual thread be returned when the application specifies the virtual=true request. We defined the true
value as a request for virtual threads to be used if possible, so the tested behavior is that the task/runnable runs and completes successfully, without asserting that the thread is virtual. Tests of virtual=false will assert that the thread is a platform
thread because in that case it is a spec requirement to have a platform thread.
The problem in the TCK is not over asserting behavior for virtual=true, the problem I have with what has been said is assuming the TCK can deploy applications with virtual=true
on Java SE 17. For those of you who are advocating vendor-specific behavior for virtual=true on Java SE 17, it needs to be clarified that vendor-specific behavior literally means the vendor can choose any behavior it wants when it sees virtual=true. A vendor
might choose to ignore the setting and use platform threads, fail at run time, fail at deploy time, run the task immediately inline, skip running the task at all, … or whatever else the vendor thinks of. The vendor can do whatever it wants, and the TCK would
somehow need to handle that.
Kyle has a solution here that will skip deploying applications with virtual=true on Java SE 17. That is really the only valid option if defining virtual=true to have
vendor-specific meaning on Java SE 17 because you cannot assume that all vendors will choose to allow the application to deploy if you leave it up to them.
We still need to have a vote on which of the three options are being chosen. I am worried it will end up as a 3-way split with none having majority support.
Ondro and others, > Therefore I suggest that we change the existing virtual thread tests in the TCK so that they don't validate anything about virtual threads.
They should just ensure that an app with virtual=true can be deployed and
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> Therefore I suggest that we change the existing virtual thread tests in the TCK so that they don't validate anything about virtual threads. They should just ensure that an app with virtual=true
can be deployed and runs as expected, regardless of whether platform or virtual threads are used.
From my understanding, the added support for Java 17 did not exclude Java 21 so as you stated we have to support running the TCK against Java 17 and Java 21.
So what I have done is added the UsingVirtualThreads annotation to the TCK which can be put on any test class that will attempt to deploy an application with `virtual=true`.
If the test is running on Java 17, the test class will be skipped and the application will never be deployed.
If the test is running on Java 21, the test class will proceed and the application will be deployed.
Furthermore, I added assumptions to any test method that makes assertions about virtual threads. This means that if a platform running on Java 21 does not support virtual threads the test
case will exit there and not attempt to make any assertions about virtual threads.
I think this hits all the points brought up in this email thread that were concerns for the TCK.
If I missed anything let me know here or on the PR.
On Wed, 7 Feb 2024 at 12:59, Steve Millidge (Payara) via cu-dev <cu-dev@xxxxxxxxxxx> wrote:
I agree with Ondro here – if we are adapting the spec to support JDK17 then we should not test anything wrt to virtual threads and just
support application deployments with that property set or missing completely.
I really don't like the decision to support Java 17, so take my opinion with a grain of salt here, please.
I think that we should minimize the impact of the decision to support Java 17 as much as possible, even if the reaction to this would not be very popular. Therefore I suggest that we change
the existing virtual thread tests in the TCK so that they don't validate anything about virtual threads. They should just ensure that an app with virtual=true can be deployed and runs as expected, regardless of whether platform or virtual threads are used.
Then the tests would pass both on Java 17 and 21.
Later, in a newer Concurrency spec version after EE 11, we can revert the tests so that they validate that the threads are virtual and require Java 21.
I think it's a good and simple solution to comply with the decision to support Java 17 and make our lives easier. Otherwise we risk more and more delays, endless discussions, and frustration.
All the best,
Director, Jakarta EE expert
Omnifish OÜ,
Narva mnt 5, 10117 Tallinn, Estonia | VAT: EE102487932
Emily and Ondro, thanks for pointing out there is a third option here to have the behavior be unspecified when virtual=true is used on Java SE 17. That would leave
it up to the vendor whether to raise an error or ignore the virtual=true value and/or issue a warning. It would also require the TCK to avoid attempting to deploy all test applications where virtual=true is used when running on Java SE 17. I discussed this
with Kyle who pointed out that is current possibly to be running the TCK test client from a Java level that is different from the Java level of the Jakarta EE product being tested, making it impossible for the TCK to accurately determine whether or not it
ought to attempt deployment of test applications with virtual=true. To address that, we would need to add a new requirement to the TCK that both must run on the same Java SE level.
I’ll post this comment to the pull request as well where this is also being discussed.
I am with Ondro on this (see here). I think using unspecified behavior might be a better option as the value is still valid but the JVM cannot fulfil the
task. Even in JVM 21, the app might not get a VT even though the app asks for a VT. EmilyOn
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I am with Ondro on this (see
here). I think using unspecified behavior might be a better option as the value is still valid but the JVM cannot fulfil the task. Even in JVM 21, the app might not get a VT even though the app asks for a VT.
Ivar,
That’s an interesting idea.
> Would it be possible to provide a warning of some kind both at compile time and runtime for Option 2?
At run time, yes. The spec could require implementations to log a warning at run time when seeing the annotation. I think that would be a good idea if going with Option
2.
At compile time, even if there were a way to cause a warning at compile time, it would be wrong to do so because it is a valid scenario to compile your application
with Java SE 17 but run it on Java SE 21. Users should not have to receive a warning for that.
On Fri, Feb 2, 2024 at 9: 09
AM Nathan Rauh via cu-dev <cu-dev@ eclipse. org>
wrote: If anyone else has an opinion on what the behavior of virtual=true should be when running on Java SE 17, please comment in https: //github. com/jakartaee/concurrency/pull/415
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1.
It’s an error because Java SE 17 can’t possibly ever honor your request to use virtual threads.
2.
Ignore your request for a virtual thread on Java SE 17 and use a platform thread instead.
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