# HG changeset patch
# User Doug Simon <doug.simon@oracle.com>
# Date 1407155285 -7200
# Node ID c53c0c153d73f8491fd35ed8ea6547c98b804b10
# Parent  58622d6b109711642782ccd4f8ab503659f67ad5
gracefully handle ConcurrentModificationException while iterating over system properties during initialization of the Debug class

diff -r 58622d6b1097 -r c53c0c153d73 graal/com.oracle.graal.debug/src/com/oracle/graal/debug/Debug.java
--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/Debug.java	Mon Aug 04 14:26:29 2014 +0200
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/Debug.java	Mon Aug 04 14:28:05 2014 +0200
@@ -1082,19 +1082,31 @@
     static {
         Set<String> metrics = new HashSet<>();
         Set<String> timers = new HashSet<>();
-        for (Map.Entry<Object, Object> e : System.getProperties().entrySet()) {
-            String name = e.getKey().toString();
-            if (name.startsWith(ENABLE_METRIC_PROPERTY_NAME_PREFIX) && Boolean.parseBoolean(e.getValue().toString())) {
-                metrics.add(name.substring(ENABLE_METRIC_PROPERTY_NAME_PREFIX.length()));
-            }
-            if (name.startsWith(ENABLE_TIMER_PROPERTY_NAME_PREFIX) && Boolean.parseBoolean(e.getValue().toString())) {
-                timers.add(name.substring(ENABLE_TIMER_PROPERTY_NAME_PREFIX.length()));
-            }
-        }
+        parseMetricAndTimerSystemProperties(metrics, timers);
         enabledMetrics = metrics.isEmpty() ? null : metrics;
         enabledTimers = timers.isEmpty() ? null : timers;
     }
 
+    protected static void parseMetricAndTimerSystemProperties(Set<String> metrics, Set<String> timers) {
+        do {
+            try {
+                for (Map.Entry<Object, Object> e : System.getProperties().entrySet()) {
+                    String name = e.getKey().toString();
+                    if (name.startsWith(ENABLE_METRIC_PROPERTY_NAME_PREFIX) && Boolean.parseBoolean(e.getValue().toString())) {
+                        metrics.add(name.substring(ENABLE_METRIC_PROPERTY_NAME_PREFIX.length()));
+                    }
+                    if (name.startsWith(ENABLE_TIMER_PROPERTY_NAME_PREFIX) && Boolean.parseBoolean(e.getValue().toString())) {
+                        timers.add(name.substring(ENABLE_TIMER_PROPERTY_NAME_PREFIX.length()));
+                    }
+                }
+                return;
+            } catch (ConcurrentModificationException e) {
+                // Iterating over the system properties may race with another thread that is
+                // updating the system properties. Simply try again in this case.
+            }
+        } while (true);
+    }
+
     /**
      * Creates a {@linkplain DebugTimer timer} that is enabled iff debugging is
      * {@linkplain #isEnabled() enabled} or the system property whose name is formed by adding to