From a20db7c8e8e630a9efc5f34cd2562c114bb7def6 Mon Sep 17 00:00:00 2001
From: Nathan Baltzell <baltzell@gmx.com>
Date: Tue, 15 Sep 2026 15:49:43 -0400
Subject: [PATCH 1/4] simplify decoder pool

---
 .../java/org/jlab/io/clara/Clas12Writer.java  |  2 --
 .../jlab/detector/decode/CLASDecoderPool.java | 19 ++++---------------
 .../org/jlab/clas/reco/DecoderEngine.java     |  4 ++--
 3 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/common-tools/clara-io/src/main/java/org/jlab/io/clara/Clas12Writer.java b/common-tools/clara-io/src/main/java/org/jlab/io/clara/Clas12Writer.java
index f4420dfaee..dabcdb132c 100644
--- a/common-tools/clara-io/src/main/java/org/jlab/io/clara/Clas12Writer.java
+++ b/common-tools/clara-io/src/main/java/org/jlab/io/clara/Clas12Writer.java
@@ -3,8 +3,6 @@
 import java.io.File;
 import java.nio.file.Path;
 import java.util.List;
-import java.util.TreeMap;
-import java.util.TreeSet;
 import org.jlab.clara.std.services.EventWriterException;
 import org.jlab.detector.calib.utils.ConstantsManager;
 import org.jlab.detector.helicity.HelicitySequenceDelayed;
diff --git a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
index 80430583ee..370a15d156 100644
--- a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
+++ b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
@@ -6,16 +6,14 @@
  *
  * @author baltzell
  */
-public class CLASDecoderPool {
+public class CLASDecoderPool extends ConcurrentLinkedQueue<CLASDecoder> {
    
-    ConcurrentLinkedQueue<CLASDecoder> pool;
-
     int sharedConstantsManagers = 64;
 
     public CLASDecoderPool(int size, String variation, String timestamp) {
 
-        pool = new ConcurrentLinkedQueue<>();
-        
+        super();
+
         CLASDecoder d0 = null;
         
         for (int i=0; i<size; i++) {
@@ -30,16 +28,7 @@ public CLASDecoderPool(int size, String variation, String timestamp) {
             }
             else d = new CLASDecoder(d0);
             
-            pool.add(d);
+            add(d);
         }
     }
-
-    public CLASDecoder take() throws InterruptedException {
-        return pool.poll();
-    }
-
-    public void put(CLASDecoder decoder) throws InterruptedException {
-        pool.offer(decoder);
-    }
-
 }
\ No newline at end of file
diff --git a/common-tools/clas-reco/src/main/java/org/jlab/clas/reco/DecoderEngine.java b/common-tools/clas-reco/src/main/java/org/jlab/clas/reco/DecoderEngine.java
index 319b5f9ca4..8ddd4c0160 100644
--- a/common-tools/clas-reco/src/main/java/org/jlab/clas/reco/DecoderEngine.java
+++ b/common-tools/clas-reco/src/main/java/org/jlab/clas/reco/DecoderEngine.java
@@ -82,9 +82,9 @@ public EngineData execute(EngineData input) {
             }
             HipoDataEvent hipo;
             try {
-                CLASDecoder d = pool.take();
+                CLASDecoder d = pool.poll();
                 hipo = new HipoDataEvent(d.getDecodedEvent(evio),schema);
-                pool.put(d);
+                pool.offer(d);
                 output.setData("binary/data-hipo", hipo.getHipoEvent());
             } catch (Exception e) {
                 String msg = String.format("Error processing input event%n%n%s", ClaraUtil.reportException(e));

From a7687a615ee0931b53cc5c5c70ed15b6ebf4a79c Mon Sep 17 00:00:00 2001
From: Nathan Baltzell <baltzell@jlab.org>
Date: Wed, 16 Sep 2026 23:08:26 -0400
Subject: [PATCH 2/4] add a singleton

---
 .../java/org/jlab/detector/decode/CLASDecoderPool.java    | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
index 370a15d156..c92d9e5e1d 100644
--- a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
+++ b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
@@ -31,4 +31,12 @@ public CLASDecoderPool(int size, String variation, String timestamp) {
             add(d);
         }
     }
+
+    static CLASDecoderPool instance = null;
+
+    public static CLASDecoderPool getInstance() {
+        if (instance == null) 
+            instance = new CLASDecoderPool(64,"default",null);
+        return instance;
+    }
 }
\ No newline at end of file

From 44e7ecdce4bba97ec6d2985d61d4d607f7778ff7 Mon Sep 17 00:00:00 2001
From: Nathan Baltzell <baltzell@jlab.org>
Date: Wed, 16 Sep 2026 23:10:35 -0400
Subject: [PATCH 3/4] fix thread-safety

---
 .../src/main/java/org/jlab/detector/decode/CLASDecoderPool.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
index c92d9e5e1d..eb366e218c 100644
--- a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
+++ b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
@@ -32,7 +32,7 @@ public CLASDecoderPool(int size, String variation, String timestamp) {
         }
     }
 
-    static CLASDecoderPool instance = null;
+    volatile static CLASDecoderPool instance = null;
 
     public static CLASDecoderPool getInstance() {
         if (instance == null) 

From ef7acc2177120c53ce70a92ab9bfee4bf5377ed6 Mon Sep 17 00:00:00 2001
From: Nathan Baltzell <baltzell@gmx.com>
Date: Thu, 17 Sep 2026 15:14:29 -0400
Subject: [PATCH 4/4] requires synchronized

---
 .../src/main/java/org/jlab/detector/decode/CLASDecoderPool.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
index eb366e218c..8acd795fa4 100644
--- a/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
+++ b/common-tools/clas-detector/src/main/java/org/jlab/detector/decode/CLASDecoderPool.java
@@ -34,7 +34,7 @@ public CLASDecoderPool(int size, String variation, String timestamp) {
 
     volatile static CLASDecoderPool instance = null;
 
-    public static CLASDecoderPool getInstance() {
+    public static synchronized CLASDecoderPool getInstance() {
         if (instance == null) 
             instance = new CLASDecoderPool(64,"default",null);
         return instance;