[🐛 Bug]: Selenium 4.26.0 has memory leak.

[shinobi01]

What happened?

I'm using Java + Cucumber + testNG + Appium to do automation test on mobile devices. I got some errors as following
Caused by: java.lang.OutOfMemoryError: Compressed class space
So I checked with VisualVM, the Metaspace and Classes are always increasing.

The loaded classs are not unloaded.
After downgrade to 4.23.0, this issue is gone

How can we reproduce the issue?

Sorry I can't share my code, but create a cucumber test cases and rerun it several times should be able to reproduce.

Relevant log output

Please refer to dump files (if any exist) [date].dump, [date]-jvmRun[N].dump and [date].dumpstream.
Exception in provider
org.apache.maven.surefire.booter.SurefireExecutionException: Exception in provider
	at org.apache.maven.plugin.surefire.InPluginVMSurefireStarter.runSuitesInProcess(InPluginVMSurefireStarter.java:91)
	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeProvider(AbstractSurefireMojo.java:1144)
	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeAfterPreconditionsChecked(AbstractSurefireMojo.java:1002)
	at org.apache.maven.plugin.surefire.AbstractSurefireMojo.execute(AbstractSurefireMojo.java:848)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:126)
	at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2(MojoExecutor.java:328)
	at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute(MojoExecutor.java:316)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:174)
	at org.apache.maven.lifecycle.internal.MojoExecutor.access$000(MojoExecutor.java:75)
	at org.apache.maven.lifecycle.internal.MojoExecutor$1.run(MojoExecutor.java:162)
	at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute(DefaultMojosExecutionStrategy.java:39)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:159)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:105)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:73)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:53)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:118)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:261)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:173)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:101)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:906)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:283)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:206)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:255)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:201)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:361)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:314)
	at org.codehaus.classworlds.Launcher.main(Launcher.java:41)
Caused by: java.lang.OutOfMemoryError: Compressed class space

Operating System

macos 14.4.1

Selenium version

Java 17 + Java-Client 9.3.0 (Selenium 4.26.0)

What are the browser(s) and version(s) where you see this issue?

Android and iOS

What are the browser driver(s) and version(s) where you see this issue?

None

Are you using Selenium Grid?

None

[github-actions]

@shinobi01, thank you for creating this issue. We will troubleshoot it as soon as we can.

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Thank you!

[joerg1985]

@shinobi01 could you share a histogram of your memory dump? The easiest way is to call jmap -histo {pid}

It would be helpful to know the exact version when it did break. Thanks in advance

[shinobi01]

@joerg1985 This is the log running on Linux jenkins slave. hs_err_pid51968.log
The first time I have this error is on September, but the reproduce rate is not frequently.
But on 4.26.0, it is 100% reproduce.

[joerg1985]

@shinobi01 this crash dump does not contain the infos i need, the output should look like this

[shinobi01]

Test start
jmap.txt
5 minutes later
jmap2.txt

[joerg1985]

@shinobi01 are you using the WebDriverDecorator?
I think i could reproduce the root issue, each invocation does return a new class.
Are you intentionally keeping hunderts references to WebElements found?
Each WebElement brings it's own class definition, due to the Proxy and this could kill your class space.

This is a extension to the DecoratedWebDriverTest to reproduce the issue.

  @Test
  void doesNotCreateTooManyClasses() {
    final WebElement found = mock(WebElement.class);
    Function<WebDriver, WebElement> f = $ -> $.findElement(By.id("test"));
    Fixture fixture = new Fixture();
    when(f.apply(fixture.original)).thenReturn(found);

    WebElement proxy1 = f.apply(fixture.decorated);
    WebElement proxy2 = f.apply(fixture.decorated);
    WebElement proxy3 = f.apply(fixture.decorated);

    assertThat(proxy1.getClass()).isSameAs(proxy2.getClass());
    assertThat(proxy1.getClass()).isSameAs(proxy3.getClass());
  }

[shinobi01]

@joerg1985 sorry, i have no idea about WebDriverDecorator, i started the webdriver by using selenide appium.

[joerg1985]

This might be related to appium/java-client#2119 but in any case the WebDriverDercorator does create to mutch classes without the PR above.