[jboss-jira] [JBoss JIRA] (WFCORE-4329) The launcher API may incorrectly assume the JVM is a non-modular JVM

[James Perkins (Jira)]

    [ https://issues.jboss.org/browse/WFCORE-4329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13695763#comment-13695763 ] 

James Perkins commented on WFCORE-4329:
---------------------------------------

Note that for a JRE the {{release}} file does not exist. It's only in the JDK. This would cause Java 8 to always launch a new process to validate whether this is a modular JVM or not.

> The launcher API may incorrectly assume the JVM is a non-modular JVM
> --------------------------------------------------------------------
>
>                 Key: WFCORE-4329
>                 URL: https://issues.jboss.org/browse/WFCORE-4329
>             Project: WildFly Core
>          Issue Type: Bug
>          Components: Launcher
>            Reporter: James Perkins
>            Assignee: James Perkins
>            Priority: Major
>
> The launcher API checks the {{$JAVA_HOME/jmods}} directory and if missing assumes it's a non-modular JVM, e.g. Java 8 or lower. In some cases this directory does not exist. We need a better way to determine the JVM version.
> It's done in the wildfly-maven-plugin like:
> {code}
>     /**
>      * Checks to see if the {@code javaHome} is a modular JVM.
>      *
>      * @param javaHome the Java Home if {@code null} an attempt to discover the Java Home will be done
>      *
>      * @return {@code true} if this is a modular environment
>      */
>     public static boolean isModularJvm(final Path javaHome) {
>         boolean result;
>         final List<String> cmd = new ArrayList<>();
>         cmd.add(getJavaCommand(javaHome));
>         cmd.add("--add-modules=java.se");
>         cmd.add("-version");
>         final ProcessBuilder builder = new ProcessBuilder(cmd);
>         Process process = null;
>         Path stdout = null;
>         try {
>             // Create a temporary file for stdout
>             stdout = Files.createTempFile("stdout", ".txt");
>             process = builder.redirectErrorStream(true)
>                     .redirectOutput(stdout.toFile()).start();
>             if (process.waitFor(1, TimeUnit.SECONDS)) {
>                 result = process.exitValue() == 0;
>             } else {
>                 if (LOGGER.isDebugEnabled()) {
>                     LOGGER.debug(getStdoutMessage("The process timed out waiting for the response.", stdout));
>                 }
>                 result = false;
>             }
>         } catch (IOException | InterruptedException e) {
>             if (LOGGER.isDebugEnabled()) {
>                 LOGGER.debug(getStdoutMessage("The process ended in error.", stdout), e);
>             }
>             result = false;
>         } finally {
>             if (process != null && process.isAlive()) {
>                 process.destroyForcibly();
>             }
>             if (stdout != null) {
>                 try {
>                     Files.deleteIfExists(stdout);
>                 } catch (IOException ignore) {
>                 }
>             }
>         }
>         return result;
>     }
> {code}
> This works, however requires a new process to be created and launched which is not ideal.
> It does look like there might be a {{$JAVA_HOME/release}} file which looks like a properties file with the {{JAVA_VERSION}} property. However we need to determine if all vendors include this file.



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