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UNOMI-930: sync startup log display to avoid to see it twice #749

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UNOMI-930: sync startup log display to avoid to see it twice #749

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59 changes: 31 additions & 28 deletions lifecycle-watcher/src/main/java/org/apache/unomi/lifecycle/BundleWatcherImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,9 @@ public class BundleWatcherImpl implements SynchronousBundleListener, ServiceList

private List<ServerInfo> serverInfos = new ArrayList<>();

// Lock object to synchronize startup message display
private final Object startupMessageLock = new Object();
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@sergehuber sergehuber Feb 10, 2026

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startupMessageAlreadyDisplayed should be declared volatile here, because it is read outside the synchronized block (line 290) as part of a double-checked locking pattern. Without volatile, the Java Memory Model allows a thread to read a stale cached value indefinitely — meaning a thread could keep seeing false even after another thread has set it to true inside the lock. In practice, stale reads are rare on strongly-ordered architectures like x86 (which is why the bug may not show up during development), but they are much more frequent on weakly-ordered architectures like ARM — commonly used in cloud/container deployments. Adding volatile guarantees that every write is immediately visible to all threads, which is what makes the outer check reliable.

References:


public void setRequiredBundles(Map<String, Boolean> requiredBundles) {
this.requiredBundles = new ConcurrentHashMap<>(requiredBundles);
}
Expand Down Expand Up @@ -274,43 +277,43 @@ private void destroyScheduler() {
}

private void checkStartupComplete() {
if (!isStartupComplete()) {
startScheduler(getBundleCheckTask());
return;
}
if (scheduledFuture != null) {
destroyScheduler();
}
if (!allAdditionalBundleStarted()) {
if (!isStartupComplete()) {
startScheduler(getBundleCheckTask());
return;
} else if (!allAdditionalBundleStarted()) {
startScheduler(getAdditionalBundleCheckTask());
return;
}
if (scheduledFuture != null) {
destroyScheduler();
}
if (!startupMessageAlreadyDisplayed) {
long totalStartupTime = System.currentTimeMillis() - startupTime;
synchronized (startupMessageLock) {
if (!startupMessageAlreadyDisplayed) {
long totalStartupTime = System.currentTimeMillis() - startupTime;

List<String> logoLines = serverInfos.get(serverInfos.size() - 1).getLogoLines();
if (logoLines != null && !logoLines.isEmpty()) {
logoLines.forEach(System.out::println);
List<String> logoLines = serverInfos.get(serverInfos.size() - 1).getLogoLines();
if (logoLines != null && !logoLines.isEmpty()) {
logoLines.forEach(System.out::println);
}
System.out.println("--------------------------------------------------------------------------------------------");
serverInfos.forEach(serverInfo -> {
String versionMessage = MessageFormat.format(" {0} {1} ({2,date,yyyy-MM-dd HH:mm:ssZ} // {3} // {4} // {5}) ",
StringUtils.rightPad(serverInfo.getServerIdentifier(), 12, " "), serverInfo.getServerVersion(),
serverInfo.getServerBuildDate(), serverInfo.getServerTimestamp(), serverInfo.getServerScmBranch(),
serverInfo.getServerBuildNumber());
System.out.println(versionMessage);
LOGGER.info(versionMessage);
});
System.out.println("--------------------------------------------------------------------------------------------");
System.out.println("Server successfully started " + requiredBundles.size() + " bundles and " + requiredServicesFilters.size()
+ " required " + "services in " + totalStartupTime + " ms");
LOGGER.info("Server successfully started {} bundles and {} required services in {} ms", requiredBundles.size(),
requiredServicesFilters.size(), totalStartupTime);
startupMessageAlreadyDisplayed = true;
shutdownMessageAlreadyDisplayed = false;
}
}
System.out.println("--------------------------------------------------------------------------------------------");
serverInfos.forEach(serverInfo -> {
String versionMessage = MessageFormat.format(" {0} {1} ({2,date,yyyy-MM-dd HH:mm:ssZ} // {3} // {4} // {5}) ",
StringUtils.rightPad(serverInfo.getServerIdentifier(), 12, " "), serverInfo.getServerVersion(),
serverInfo.getServerBuildDate(), serverInfo.getServerTimestamp(), serverInfo.getServerScmBranch(),
serverInfo.getServerBuildNumber());
System.out.println(versionMessage);
LOGGER.info(versionMessage);
});
System.out.println("--------------------------------------------------------------------------------------------");
System.out.println("Server successfully started " + requiredBundles.size() + " bundles and " + requiredServicesFilters.size()
+ " required " + "services in " + totalStartupTime + " ms");
LOGGER.info("Server successfully started {} bundles and {} required services in {} ms", requiredBundles.size(),
requiredServicesFilters.size(), totalStartupTime);
startupMessageAlreadyDisplayed = true;
shutdownMessageAlreadyDisplayed = false;
}
}

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