NPE on Windows using "Git for Windows" (MINGW)

[baumato]

I use Git for Windows (https://git-scm.com/download/win). When executing
mvnd --version
nothing happens until I press Enter for the second time. Then the result is:

$ mvnd --version
Exception in thread "Thread-0" java.lang.NullPointerException
        at org.mvndaemon.mvnd.common.logging.TerminalOutput.readInputLoop(TerminalOutput.java:451)
        at java.lang.Thread.run(Thread.java:834)
        at com.oracle.svm.core.thread.JavaThreads.threadStartRoutine(JavaThreads.java:519)
        at com.oracle.svm.core.windows.WindowsJavaThreads.osThreadStartRoutine(WindowsJavaThreads.java:138)
mvnd native client 0.4.3-windows-amd64 (e20989ddd440928f392f839c282c6ef196107404)
Terminal: org.jline.terminal.impl.PosixSysTerminal with pty org.jline.terminal.impl.ExecPty
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: C:\Apps\mvnd\mvn
Java version: 1.8.0_261, vendor: Oracle Corporation, runtime: C:\Apps\jdk8\jre
Default locale: de_DE, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

Since Git for Windows uses MINGW
$ env | grep MSYSTEM
MSYSTEM_CARCH=x86_64
MSYSTEM_CHOST=x86_64-w64-mingw32
MSYSTEM_PREFIX=/mingw64
MSYSTEM=MINGW64
JLine provides a PosixSysTerminal. May this be related?

Update:
When I override the environment variable MSYSTEM, I get following output:

$ old=$MSYSTEM; echo old=$old; MSYSTEM=""; mvnd --version; MSYSTEM=$old; echo $MSYSTEM
old=MINGW64
Mar 29, 2021 3:41:54 PM org.jline.utils.Log logr
WARNING: Unable to create a system terminal, creating a dumb terminal (enable debug logging for more information)
mvnd native client 0.4.3-windows-amd64 (e20989ddd440928f392f839c282c6ef196107404)
Terminal: org.jline.terminal.impl.DumbTerminal
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: C:\hlag\Apps\FIDE\mvnd\mvn
Java version: 1.8.0_261, vendor: Oracle Corporation, runtime: C:\hlag\Apps\FIDE\jdk8\jre
Default locale: de_DE, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"
MINGW64

This works, but I cannot enjoy the nice ouput that is usually available.

[baumato]

When using
Terminal: org.jline.terminal.impl.PosixSysTerminal with pty org.jline.terminal.impl.ExecPty
then the call of read(10) within the readInputLoop in TerminalOutput is blocking forever. Reading the documentation of the method, this should not be the case.

   void readInputLoop() {
        try {
            while (!closing) {
                if (readInput.readLock().tryLock(10, TimeUnit.MILLISECONDS)) {
                    int c = terminal.reader().read(10);
                    if (c == -1) {
                        break;
                    }
                    if (c == KEY_PLUS || c == KEY_MINUS || c == KEY_CTRL_L || c == KEY_CTRL_M || c == KEY_CTRL_B) {
                        daemonReceive.accept(Message.keyboardInput((char) c));
                    }
                    readInput.readLock().unlock();
                }
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        } catch (InterruptedIOException e) {
            Thread.currentThread().interrupt();
        } catch (IOException e) {
            this.exception = e;
        }
    }

Analysis is ongoing!

[baumato]

Cannot figure it out. Directly after starting mvnd the program hangs. Thread dump is:

3XMTHREADINFO3           Java callstack:
4XESTACKTRACE                at java/io/FileInputStream.readBytes(Native Method)
4XESTACKTRACE                at java/io/FileInputStream.read(FileInputStream.java:279)
4XESTACKTRACE                at java/io/BufferedInputStream.fill(BufferedInputStream.java:252)
4XESTACKTRACE                at java/io/BufferedInputStream.read(BufferedInputStream.java:271)
5XESTACKTRACE                   (entered lock: java/io/BufferedInputStream@0x00000007FFEA64F8, entry count: 1)
4XESTACKTRACE                at org/jline/utils/ExecHelper.waitAndCapture(ExecHelper.java:58)
4XESTACKTRACE                at org/jline/utils/ExecHelper.exec(ExecHelper.java:36)
4XESTACKTRACE                at org/jline/terminal/impl/ExecPty.doGetConfig(ExecPty.java:175)
4XESTACKTRACE                at org/jline/terminal/impl/ExecPty.getSize(ExecPty.java:169)
4XESTACKTRACE                at org/jline/terminal/impl/AbstractPosixTerminal.getSize(AbstractPosixTerminal.java:60)
4XESTACKTRACE                at org/mvndaemon/mvnd/common/logging/TerminalOutput.update(TerminalOutput.java:506)
4XESTACKTRACE                at org/mvndaemon/mvnd/common/logging/TerminalOutput.accept(TerminalOutput.java:191)
4XESTACKTRACE                at org/mvndaemon/mvnd/client/DefaultClient.execute(DefaultClient.java:176)
4XESTACKTRACE                at org/mvndaemon/mvnd/client/DefaultClient.main(DefaultClient.java:112)

3XMTHREADINFO3           Java callstack:
4XESTACKTRACE                at java/io/FileInputStream.read0(Native Method)
4XESTACKTRACE                at java/io/FileInputStream.read(FileInputStream.java:231)
4XESTACKTRACE                at org/jline/terminal/impl/AbstractPty$PtyInputStream.read(AbstractPty.java:73)
4XESTACKTRACE                at org/jline/utils/NonBlockingInputStream.read(NonBlockingInputStream.java:62)
4XESTACKTRACE                at org/jline/utils/NonBlocking$NonBlockingInputStreamReader.read(NonBlocking.java:168)
4XESTACKTRACE                at org/jline/utils/NonBlockingReader.read(NonBlockingReader.java:57)
4XESTACKTRACE                at org/mvndaemon/mvnd/common/logging/TerminalOutput.readInputLoop(TerminalOutput.java:446)
4XESTACKTRACE                at org/mvndaemon/mvnd/common/logging/TerminalOutput$$Lambda$84/0000000000000000.run(Bytecode PC:4)
4XESTACKTRACE                at java/lang/Thread.run(Thread.java:834)

There are two places where read from terminal happens and it seems, this is not supported by the PosixSysTerminal. It seems, we need to stick to the dump terminal.

[ghost]

Same problem here with WSL 1:

$ mvnd --status
Exception in thread "Thread-1" java.lang.NullPointerException
        at org.mvndaemon.mvnd.common.logging.TerminalOutput.readInputLoop(TerminalOutput.java:451)
        at java.lang.Thread.run(Thread.java:834)
        at com.oracle.svm.core.thread.JavaThreads.threadStartRoutine(JavaThreads.java:519)
        at com.oracle.svm.core.posix.thread.PosixJavaThreads.pthreadStartRoutine(PosixJavaThreads.java:192)
      ID      PID   Port   Status    RSS            Last activity  Java home
dc5f4fcc      158  62872     Idle   792m  2021-04-01T13:55:33.572  /mnt/c/Dev/Tools/graalvm-ce-java11-linux-21.0.0.2

[gnodet]

Same problem here with WSL 1:

$ mvnd --status
Exception in thread "Thread-1" java.lang.NullPointerException
        at org.mvndaemon.mvnd.common.logging.TerminalOutput.readInputLoop(TerminalOutput.java:451)
        at java.lang.Thread.run(Thread.java:834)
        at com.oracle.svm.core.thread.JavaThreads.threadStartRoutine(JavaThreads.java:519)
        at com.oracle.svm.core.posix.thread.PosixJavaThreads.pthreadStartRoutine(PosixJavaThreads.java:192)
      ID      PID   Port   Status    RSS            Last activity  Java home
dc5f4fcc      158  62872     Idle   792m  2021-04-01T13:55:33.572  /mnt/c/Dev/Tools/graalvm-ce-java11-linux-21.0.0.2

@Axblu Which mvnd binary are you using, the windows or the linux one ? Can you paste the output of mvnd --version ? It seems to work for me with the windows executable on WSL 1.

@baumato I've been able to reproduce the problem with MINGW. It seems setting the console into raw mode using stty does not really work, that seems to be the reason why the call to read(10) only returns when the enter key is pressed.

[ghost]

@gnodet Using the Linux binary:

$ file `which mvnd`
/home/belu/.sdkman/candidates/mvnd/current/bin/mvnd: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/l, for GNU/Linux 3.2.0, BuildID[sha1]=2b4ca6fd73459d0c580838d37f4e374c53d9ef44, with debug_info, not stripped

And the following version:

mvnd native client 0.4.3-linux-amd64 (e20989ddd440928f392f839c282c6ef196107404)
Terminal: org.jline.terminal.impl.PosixSysTerminal with pty org.jline.terminal.impl.jansi.linux.LinuxNativePty
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: /home/belu/.sdkman/candidates/mvnd/0.4.3/mvn
Java version: 11.0.10, vendor: GraalVM Community, runtime: /mnt/c/Dev/Tools/graalvm-ce-java11-linux-21.0.0.2
Default locale: en, platform encoding: UTF-8
OS name: "linux", version: "4.4.0-17763-microsoft", arch: "amd64", family: "unix"
Exception in thread "Thread-1" java.lang.RuntimeException: java.lang.InterruptedException
        at org.mvndaemon.mvnd.client.DaemonClientConnection.enqueue(DaemonClientConnection.java:141)
        at org.mvndaemon.mvnd.common.logging.TerminalOutput.readInputLoop(TerminalOutput.java:451)
        at java.lang.Thread.run(Thread.java:834)
        at com.oracle.svm.core.thread.JavaThreads.threadStartRoutine(JavaThreads.java:519)
        at com.oracle.svm.core.posix.thread.PosixJavaThreads.pthreadStartRoutine(PosixJavaThreads.java:192)
Caused by: java.lang.InterruptedException
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireInterruptibly(AbstractQueuedSynchronizer.java:1261)
        at java.util.concurrent.locks.ReentrantLock.lockInterruptibly(ReentrantLock.java:317)
        at java.util.concurrent.ArrayBlockingQueue.put(ArrayBlockingQueue.java:364)
        at org.mvndaemon.mvnd.client.DaemonClientConnection.enqueue(DaemonClientConnection.java:139)
        ... 4 more