RFR [9] 8156841: sun.security.pkcs11.SunPKCS11 poller thread retains a strong reference to the context class loader

[Chris Hegarty]

The SunPKCS11 poller thread has no need of any user defined class loader,
so should set its context class loader to null before starting, so as to not
inadvertently retain a reference to the creating thread’s context class loader.

In other areas that suffered from a similar issue we changed to use an
InnocuousThread, but I cannot fully satisfy myself that this is a safe
substation here, so I opted for the safest minimal fix. A future refactoring
exercise should consider using InnocuousThread. 

diff -r 92c31ec731eb src/jdk.crypto.pkcs11/share/classes/sun/security/pkcs11/SunPKCS11.java
--- a/src/jdk.crypto.pkcs11/share/classes/sun/security/pkcs11/SunPKCS11.java	Wed Aug 10 11:54:12 2016 +0100
+++ b/src/jdk.crypto.pkcs11/share/classes/sun/security/pkcs11/SunPKCS11.java	Wed Aug 10 16:32:41 2016 +0100
@@ -809,20 +809,21 @@
         }
     }
 
     // create the poller thread, if not already active
     private void createPoller() {
         if (poller != null) {
             return;
         }
         final TokenPoller poller = new TokenPoller(this);
         Thread t = new Thread(null, poller, "Poller " + getName(), 0, false);
+        t.setContextClassLoader(null);
         t.setDaemon(true);
         t.setPriority(Thread.MIN_PRIORITY);
         t.start();
         this.poller = poller;
     }
 
     // destroy the poller thread, if active
     private void destroyPoller() {
         if (poller != null) {
             poller.disable();

https://bugs.openjdk.java.net/browse/JDK-8156841

-Chris.