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https://issues.apache.org/jira/browse/DRILL-7360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16917012#comment-16917012
]
ASF GitHub Bot commented on DRILL-7360:
---------------------------------------
sohami commented on pull request #1848: DRILL-7360: Refactor WatchService in
Drillbit class and fix concurrency issues
URL: https://github.com/apache/drill/pull/1848#discussion_r318241977
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/server/Drillbit.java
##########
@@ -371,66 +376,98 @@ private void javaPropertiesToSystemOptions() {
}
}
-
- // Polls for graceful file to check if graceful shutdown is triggered from
the script.
+ /**
+ * Polls for graceful file to check if graceful shutdown is triggered from
the script.
+ */
private static class GracefulShutdownThread extends Thread {
+ private static final String DRILL_HOME = "DRILL_HOME";
+ private static final String GRACEFUL_SIGFILE = "GRACEFUL_SIGFILE";
+ private static final String NOT_SUPPORTED_MESSAGE = "Graceful shutdown
from command line will not be supported.";
+
private final Drillbit drillbit;
private final StackTrace stackTrace;
- GracefulShutdownThread(final Drillbit drillbit, final StackTrace
stackTrace) {
+
+ GracefulShutdownThread(Drillbit drillbit, StackTrace stackTrace) {
this.drillbit = drillbit;
this.stackTrace = stackTrace;
+
+ setName("Drillbit-Graceful-Shutdown#" + getName());
}
@Override
public void run () {
try {
- pollShutdown(drillbit);
- } catch (InterruptedException e) {
- logger.debug("Interrupted GracefulShutdownThread");
+ pollShutdown();
+ } catch (InterruptedException e) {
+ drillbit.interruptPollShutdown = false;
+ logger.debug("Graceful Shutdown thread was interrupted", e);
} catch (IOException e) {
- throw new RuntimeException("Caught exception while polling for
gracefulshutdown\n" + stackTrace, e);
+ throw new RuntimeException("Exception while polling for graceful
shutdown\n" + stackTrace, e);
}
}
- /*
- * Poll for the graceful file, if the file is found cloase the drillbit.
In case if the DRILL_HOME path is not
- * set, graceful shutdown will not be supported from the command line.
+ /**
+ * Poll for the graceful file, if the file is found or modified, close the
Drillbit.
+ * In case if the {@link #DRILL_HOME} or {@link #GRACEFUL_SIGFILE}
environment variables are not set,
+ * graceful shutdown will not be supported from the command line.
*/
- private void pollShutdown(Drillbit drillbit) throws IOException,
InterruptedException {
- final String drillHome = System.getenv("DRILL_HOME");
- final String gracefulFile = System.getenv("GRACEFUL_SIGFILE");
- final Path drillHomePath;
+ private void pollShutdown() throws IOException, InterruptedException {
+ String drillHome = System.getenv(DRILL_HOME);
+ String gracefulFile = System.getenv(GRACEFUL_SIGFILE);
+ Path drillHomePath;
if (drillHome == null || gracefulFile == null) {
- logger.warn("Cannot access graceful file. Graceful shutdown from
command line will not be supported.");
+ if (logger.isWarnEnabled()) {
+ StringBuilder builder = new StringBuilder(NOT_SUPPORTED_MESSAGE);
+ if (drillHome == null) {
+ builder.append(" ").append(DRILL_HOME).append(" is not set.");
+ }
+ if (gracefulFile == null) {
+ builder.append(" ").append(GRACEFUL_SIGFILE).append(" is not
set.");
+ }
+ logger.warn(builder.toString());
+ }
return;
}
try {
drillHomePath = Paths.get(drillHome);
+ if (!Files.exists(drillHomePath)) {
+ logger.warn("{} path [{}] does not exist. {}", DRILL_HOME,
drillHomePath, NOT_SUPPORTED_MESSAGE);
+ return;
+ }
} catch (InvalidPathException e) {
- logger.warn("Cannot access graceful file. Graceful shutdown from
command line will not be supported.");
+ logger.warn("Unable to construct {}} path [{}]: {}. {}",
+ DRILL_HOME, drillHome, e.getMessage(), NOT_SUPPORTED_MESSAGE);
return;
}
- boolean triggered_shutdown = false;
- WatchKey wk = null;
- try (final WatchService watchService =
drillHomePath.getFileSystem().newWatchService()) {
- drillHomePath.register(watchService,
StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_CREATE);
- while (!triggered_shutdown) {
- wk = watchService.take();
- for (WatchEvent<?> event : wk.pollEvents()) {
- final Path changed = (Path) event.context();
- if (changed != null && changed.endsWith(gracefulFile)) {
- drillbit.interruptPollShutdown = false;
- triggered_shutdown = true;
- drillbit.close();
+
+ poll(drillHomePath, gracefulFile);
+ }
+
+ private void poll(Path drillHomePath, String gracefulFile) throws
IOException, InterruptedException {
+ while (true) {
+ try (WatchService watchService =
drillHomePath.getFileSystem().newWatchService()) {
+ drillHomePath.register(watchService,
StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_MODIFY);
+ while (true) {
+ WatchKey watchKey = watchService.take();
+ for (WatchEvent<?> event : watchKey.pollEvents()) {
+ if (StandardWatchEventKinds.OVERFLOW != event.kind()) {
+ Path changedPath = (Path) event.context();
+ if (changedPath != null && changedPath.endsWith(gracefulFile))
{
+ drillbit.interruptPollShutdown = false;
+ drillbit.close();
+ return;
+ }
+ }
+ }
+
+ if (!watchKey.reset()) {
+ // if watch key is no longer valid, exit Watch Service loop
+ // and attempt to re-register Drill home path in Watch Service
Review comment:
please add a debug log here to keep track of these events.
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> Refactor WatchService code in Drillbit class
> --------------------------------------------
>
> Key: DRILL-7360
> URL: https://issues.apache.org/jira/browse/DRILL-7360
> Project: Apache Drill
> Issue Type: Task
> Affects Versions: 1.16.0
> Reporter: Arina Ielchiieva
> Assignee: Arina Ielchiieva
> Priority: Major
> Fix For: 1.17.0
>
>
> Refactor WatchService to user proper code (see
> https://docs.oracle.com/javase/tutorial/essential/io/notification.html for
> details) in Drillbit class and fix concurrency issues connected with
> variables assigning from different thread.
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