Michael Pradel created JBCOMMON-126: --------------------------------------- Summary: NullPointerException when using PropertyMap concurrently Key: JBCOMMON-126 URL: https://issues.jboss.org/browse/JBCOMMON-126 Project: JBoss Common Issue Type: Bug Security Level: Public (Everyone can see) Components: common-core (2.x) Affects Versions: 2.2.18.GA Environment: All environments Reporter: Michael Pradel PropertyMap extends Properties, which is a thread-safe class, but it doesn't preserve its thread safety. This leads to surprising crashes if you have a reference of type Properties (documented as thread-safe) that turns out to be a PropertyMap (not thread-safe). Here's a simplified example that shows how we hit this bug: final Properties p = getProps(); p.setProperty("a", "b"); Thread t1 = new Thread(new Runnable() { public void run() { p.remove("a"); } }); Thread t2 = new Thread(new Runnable() { public void run() { p.clear(); } }); t1.start(); t2.start(); try { t1.join(); t2.join(); } catch (InterruptedException e) { e.printStackTrace(); } Properties getProps() { // return new Properties(); // OK return new PropertyMap(); // leads to NullPointerException } The code runs fine if getProps returns Properties (as it should, because Properties is thread-safe), but raises a NullPointerException if getProps returns a PropertyMap. Are you aware of this inconsistency? It seems that the safest way of extending Properties is to make methods that override synchronized methods synchronized. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.jboss.org/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira