[tomcat] 05/05: Fix BZ 65454. Correct a timing issue that could delay a request

[markt]

This is an automated email from the ASF dual-hosted git repository.

markt pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/tomcat.git

commit 0f2e084d1583cfa4c00cec1958ec30113fb4f41e
Author: Mark Thomas <ma...@apache.org>
AuthorDate: Wed Jul 21 17:45:01 2021 +0100

    Fix BZ 65454. Correct a timing issue that could delay a request
    
    https://bz.apache.org/bugzilla/show_bug.cgi?id=65454
    If the work queue is not empty, it is likely that a task was added to
    the work queue between this thread timing out and the worker count being
    decremented a few lines above this comment. In this case, create a
    replacement worker so that the task isn't held in the queue waiting for
    one of the other workers to finish.
---
 java/org/apache/tomcat/util/threads/ThreadPoolExecutor.java | 10 ++++++++--
 webapps/docs/changelog.xml                                  |  6 ++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/java/org/apache/tomcat/util/threads/ThreadPoolExecutor.java 
b/java/org/apache/tomcat/util/threads/ThreadPoolExecutor.java
index 7b1ec55..8771c22 100644
--- a/java/org/apache/tomcat/util/threads/ThreadPoolExecutor.java
+++ b/java/org/apache/tomcat/util/threads/ThreadPoolExecutor.java
@@ -1050,8 +1050,14 @@ public class ThreadPoolExecutor extends 
AbstractExecutorService {
                 if (min == 0 && ! workQueue.isEmpty()) {
                     min = 1;
                 }
-                if (workerCountOf(c) >= min)
-                 {
+                // https://bz.apache.org/bugzilla/show_bug.cgi?id=65454
+                // If the work queue is not empty, it is likely that a task was
+                // added to the work queue between this thread timing out and
+                // the worker count being decremented a few lines above this
+                // comment. In this case, create a replacement worker so that
+                // the task isn't held in the queue waiting for one of the 
other
+                // workers to finish.
+                if (workerCountOf(c) >= min && workQueue.isEmpty()) {
                     return; // replacement not needed
                 }
             }
diff --git a/webapps/docs/changelog.xml b/webapps/docs/changelog.xml
index 3838cf3..cafd371 100644
--- a/webapps/docs/changelog.xml
+++ b/webapps/docs/changelog.xml
@@ -146,6 +146,12 @@
         associated with the response until the connection timed out at which
         point the final packet would be sent and the connection closed. (markt)
       </fix>
+      <fix>
+        <bug>65454</bug>: Fix a race condition that could result in a delay to
+        a new request. The new request could be queued to wait for an existing
+        request to finish processing rather than the thread pool creating a new
+        thread to process the new request. (markt)
+      </fix>
     </changelog>
   </subsection>
   <subsection name="Jasper">

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