Github user upthewaterspout commented on a diff in the pull request:
https://github.com/apache/incubator-geode/pull/299#discussion_r90077733
--- Diff:
geode-core/src/main/java/org/apache/geode/internal/statistics/StatMonitorHandler.java
---
@@ -50,36 +50,26 @@ public StatMonitorHandler() {
/** Adds a monitor which will be notified of samples */
public boolean addMonitor(StatisticsMonitor monitor) {
- synchronized (this) {
- boolean added = false;
- List<StatisticsMonitor> oldMonitors = this.monitors;
- if (!oldMonitors.contains(monitor)) {
- List<StatisticsMonitor> newMonitors = new
ArrayList<StatisticsMonitor>(oldMonitors);
- added = newMonitors.add(monitor);
- this.monitors = Collections.unmodifiableList(newMonitors);
- }
- if (!this.monitors.isEmpty()) {
- startNotifier_IfEnabledAndNotRunning();
- }
- return added;
+ boolean added = false;
--- End diff --
I don't think it's safe to remove the synchronization here. You're calling
contains followed by add followed by isEmpty. Also, startNotifier_... is
dependent on the state of this.monitors. this.monitors could be getting changed
by other threads at any point in here.
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