Summary

Degrade Thread.suspend() and Thread.resume() to throw UnsupportedOperationException (UOE) unconditionally.

Problem

Thread.suspend dates from JDK 1.0 as a user facing API to suspend a victim thread from execution. It is inherently deadlock prone. Thread.suspend and Thread.resume have been deprecated since JDK 1.2 with a link to the "Java Thread Primitive Deprecation" page that explains the reasoning for the deprecation.

The recent steps on degrading and removing the feature are:

• Thread.suspend and Thread.resume were terminally deprecated in Java 14
• ThreadGroup.suspend and ThreadGroup.resume were degraded to throw UOE in Java 19

At this time, Thread.suspend will suspend a platform thread as it always done. Both Thread.suspend and Thread.resume throw UOE if invoked on a virtual Thread.

Solution

• Re-specify Thread.suspend and Thread.resume to throw UOE.
• Update the JVM TI, JDWP and JDI specifications to drop Thread.suspend/resume as possible suspend/resume functions. This change has otherwise no impact on the suspend/resume APIs defined for debuggers.
• Minor adjustments to java.lang.IllegalThreadStateException.
• Minor updates to java.lang.SecurityManager to drop references to Thread.suspend/resume and other degraded methods that no longer call into the security manager.

Specification

A zip file with the specdiffs is attached to this CSR with changes to the docs of the following API elements:

java.lang.Thread.suspend
java.lang.Thread.resume
java.lang.IllegalThreadStateException
java.lang.SecurityManager.checkAccess(Thread)
java.lang.SecurityManager.checkAccess(ThreadGroup)
java.lang.RuntimePermission modifyThread and modifyThreadGroup targets
com.sun.jdi.ThreadReference.suspend()
com.sun.jdi.ThreadReference.resume()
com.sun.jdi.VirtualMachine.suspend()
com.sun.jdi.VirtualMachine.resume()
JDWP ThreadReference/Suspend and ThreadReference/Resume commands
JVMTI ResumeThread / ResumeThreadList functions
JVMTI GetThreadState description of JVMTI_THREAD_STATE_SUSPENDED