Find a strange problem about using project-panama on macos
刘希晨
benrush0705 at gmail.com
Mon Aug 14 12:44:01 UTC 2023
Let me add two things:
1. I am not using a symbol link, the OPENSSL dynamic library was compiled
from source, using the newest version 3.1.2
2. System.load() is the same as SymbolLookup, jmap and jconsole won't work
David Holmes <david.holmes at oracle.com> 于2023年8月14日周一 20:08写道：
> cc mailing list
>
> On 14/08/2023 6:51 pm, 刘希晨 wrote:
> > Sorry I am not an export in native debugging, it took me several hours
> > finding the actual line causing jconsole and jmap not working properly
> > on macos, and except for that, the application works perfectly well in
> > my computer, that's the reason why I haven't found the case before, so I
> > guess it's not a problem about safepoint, because if this single line
> > would cause the application not able to reach a safepoint, why would it
> > work on windows, and the application could GC well (I tested add
> > System.gc() in the above main method, and it could be done well, I think
> > that should suggest the safepoint could be reached, perhaps I am wrong,
> > I don't know much about safepoint but it seems GC needs to reach a
> > safepoint to run), it runs completely normally except can't be accessed
> > by jmap and jconsole (By the way, the application could be debugged by
> > idea properly, which is quite suprising, I am using Idea version
> > 2023.2), so I guess the openjdk21-ea implementation on macos of
> > SymbolLookup should have some problems internally.
>
> When we are dealing with native code different platforms have different
> native code and so they can behave differently. The symptoms you
> describe suggest an inability of the VM to reach a safepoint.
>
> But without getting a native stack dump from a debugger there is no way
> to investigate this further.
>
> Also please respond to the mailing list rather than directly to myself,
> so others can see what is happening.
>
> David
>
> > David Holmes <david.holmes at oracle.com <mailto:david.holmes at oracle.com>>
> > 于2023年8月14日周一 12:51写道：
> >
> > On 14/08/2023 2:45 pm, David Holmes wrote:
> > >
> > >
> > > On 14/08/2023 12:42 pm, 刘希晨 wrote:
> > >>
> > >> I have found a really strange problem when using project-panama
> on
> > >> macos, and it might be a bug.
> > >>
> > >> *Environment*: JDK-21 ea build 34, cpu : M1 Pro,
> operating system :
> > >> Ventura 13.5
> > >>
> > >> Here are the minimal reproducible codes:
> > >>
> > >> public class SimpleExample {
> > >> public static void main(String[] args)throws Throwable {
> > >> SymbolLookup crypto =
> > >>
> >
> SymbolLookup.libraryLookup("/Users/liuxichen/workspace/tenet-lib/lib/libcrypto.dylib",
> Arena.global());
> > >> Thread.sleep(Long.MAX_VALUE);
> > >> }
> > >> }
> > >>
> > >> The libcrypto.dylib file is the OPENSSL dynamic library file, I
> > think
> > >> other libraries probably could cause the same problem.
> > >>
> > >> *Problem description*:
> > >> A normal java program would work fine with *jconsole* and
> > *jmap*, if
> > >> running the above code in macos, jconsole won't be able to
> > connect to
> > >> the target process, and jmap will give the following error:
> > >>
> > >> *~/Dow/jdk-21/C/H/bin jps*
> > >>
> > >> 1665 RemoteMavenServer36
> > >> 2673 Jps
> > >> 532
> > >> 1671 Launcher
> > >> 1672 SimpleExample
> > >> 1211
> > >>
> > >>
> > >> * ~/Dow/jdk-21/C/H/bin ./jmap -histo:live,file=histo5.data 1672*
> > >>
> > >> Exception in thread"main"
> > >> com.sun.tools.attach.AttachNotSupportedException: Unable to open
> > >> socket file
> > >> /var/folders/k4/j5wzcbnd3m96s5lmqw_8lh8r0000gn/T/.java_pid1672:
> > target
> > >> process1672 doesn't respond within 10500ms or HotSpot VM not
> loaded
> > >> at
> > >>
> >
> jdk.attach/sun.tools.attach.VirtualMachineImpl.<init>(VirtualMachineImpl.java:95)
> > >> at
> > >>
> >
> jdk.attach/sun.tools.attach.AttachProviderImpl.attachVirtualMachine(AttachProviderImpl.java:58)
> > >> at
> > >>
> >
> jdk.attach/com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:207)
> > >> at
> > jdk.jcmd/sun.tools.jmap.JMap.executeCommandForPid(JMap.java:127)
> > >> at jdk.jcmd/sun.tools.jmap.JMap.histo(JMap.java:199)
> > >> at jdk.jcmd/sun.tools.jmap.JMap.main(JMap.java:112)
> > >
> > > These problems, and the workaround, suggest that a thread is
> > preventing
> > > the VM from going to safepoint, but I can't see why that should
> > be the
> > > case. If you apply the StartAttachListener workaround what does
> > jstack
> > > show you is happening?
> >
> > Actually if the VM can't reach a safepoint then jstack won't be able
> to
> > run either. You need to run a native debugger against the process and
> > get the stack traces.
> >
> > David
> > ------
> >
> > > David
> > > -----
> > >
> > >>
> > >> Several tests:
> > >> 1. The above code runs fine on windows and macos, and the process
> > >> could be accessed by jconsole and jmap on windows, only fail on
> > macos
> > >> 2. The problem could be solved by adding VM options, for jconsole
> > >> usable, add -Dcom.sun.management.jmxremote for jmap usable add
> > >> -XX:+StartAttachListener , if there is no
> > >> *SymbolLookup.libraryLookup*(), then jconsole and jmap would
> > work well
> > >> without these two arguments
> > >>
> > >> So, I guess there must be some internal logic that blocks the
> > jconsole
> > >> and jmap from entering java program inside
> > >> *SymbolLookup.libraryLookup*(), please correct me if I am wrong
> > >>
> > >>
> > >>
> >
>
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