Re: (tomcat) 02/02: Follow-up to 9a59ef2717. Fix concurrency issue.

On 17/08/2026 12:43, [email protected] wrote:
> This is an automated email from the ASF dual-hosted git repository.
> 
> markt-asf pushed a commit to branch main
> in repository https://gitbox.apache.org/repos/asf/tomcat.git
> 
> commit 949b1bcd44ba36a2bc7f39ecf154a38b0f9a7983
> Author: Mark Thomas <[email protected]>
> AuthorDate: Mon Aug 17 12:43:05 2026 +0100
> 
>      Follow-up to 9a59ef2717. Fix concurrency issue.

Just a note. This isn't ready for back-port as I am currently looking at 
refactoring this to address a similar issue in the Manager app.

Mark

> ---
>   .../catalina/session/PersistentManagerBase.java    | 15 ++++++++-----
>   .../apache/catalina/session/SortableSession.java   | 26 ++++++++++++++++++++++
>   2 files changed, 35 insertions(+), 6 deletions(-)
> 
> diff --git a/java/org/apache/catalina/session/PersistentManagerBase.java b/java/org/apache/catalina/session/PersistentManagerBase.java
> index 13d6a1fa7d..756e90fd47 100644
> --- a/java/org/apache/catalina/session/PersistentManagerBase.java
> +++ b/java/org/apache/catalina/session/PersistentManagerBase.java
> @@ -18,7 +18,6 @@ package org.apache.catalina.session;
>   
>   import java.io.IOException;
>   import java.util.Arrays;
> -import java.util.Comparator;
>   import java.util.HashMap;
>   import java.util.HashSet;
>   import java.util.Map;
> @@ -808,11 +807,17 @@ public abstract class PersistentManagerBase extends ManagerBase implements Store
>               log.debug(sm.getString("persistentManager.tooManyActive", Integer.valueOf(sessions.length)));
>           }
>   
> +        // lastAccessedTimeInternal may change so need to use a snapshot to avoid various concurrency failures.
> +        SortableSession[] sortedSessions = new SortableSession[sessions.length];
> +        for (int i = 0; i < sessions.length; i++) {
> +            sortedSessions[i] = new SortableSession(sessions[i].getLastAccessedTimeInternal(), sessions[i]);
> +        }
> +        Arrays.sort(sortedSessions);
> +
>           int toswap = sessions.length - limit;
> -        Arrays.sort(sessions, Comparator.comparingLong(Session::getLastAccessedTimeInternal));
>   
> -        for (int i = 0; i < sessions.length && toswap > 0; i++) {
> -            StandardSession session = (StandardSession) sessions[i];
> +        for (int i = 0; i < sortedSessions.length && toswap > 0; i++) {
> +            StandardSession session = (StandardSession) sortedSessions[i].session();
>               synchronized (session) {
>                   int timeIdle = (int) (session.getIdleTimeInternal() / 1000L);
>                   if (timeIdle >= minIdleSwap) {
> @@ -833,7 +838,6 @@ public abstract class PersistentManagerBase extends ManagerBase implements Store
>                   }
>               }
>           }
> -
>       }
>   
>   
> @@ -877,6 +881,5 @@ public abstract class PersistentManagerBase extends ManagerBase implements Store
>               }
>           }
>       }
> -
>   }
>   
> diff --git a/java/org/apache/catalina/session/SortableSession.java b/java/org/apache/catalina/session/SortableSession.java
> new file mode 100644
> index 0000000000..0e876e442a
> --- /dev/null
> +++ b/java/org/apache/catalina/session/SortableSession.java
> @@ -0,0 +1,26 @@
> +/*
> + * Licensed to the Apache Software Foundation (ASF) under one or more
> + * contributor license agreements.  See the NOTICE file distributed with
> + * this work for additional information regarding copyright ownership.
> + * The ASF licenses this file to You under the Apache License, Version 2.0
> + * (the "License"); you may not use this file except in compliance with
> + * the License.  You may obtain a copy of the License at
> + *
> + *      http://www.apache.org/licenses/LICENSE-2.0
> + *
> + * Unless required by applicable law or agreed to in writing, software
> + * distributed under the License is distributed on an "AS IS" BASIS,
> + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
> + * See the License for the specific language governing permissions and
> + * limitations under the License.
> + */
> +package org.apache.catalina.session;
> +
> +import org.apache.catalina.Session;
> +
> +public record SortableSession(long timestamp, Session session) implements Comparable<SortableSession> {
> +    @Override
> +    public int compareTo(SortableSession o) {
> +        return Long.compare(timestamp, o.timestamp);
> +    }
> +}
> \ No newline at end of file
> 
> 
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