Synchronize open/close on class as well as instance

build.gradle

@@ -7,7 +7,7 @@ buildscript {
 
 plugins {
   id 'maven-publish'
-  id 'biz.aQute.bnd.builder' version '5.0.0'
+  id 'biz.aQute.bnd.builder' version '6.0.0'
 }
 
 group = 'com.fazecast'

src/main/java/com/fazecast/jSerialComm/SerialPort.java

@@ -2,7 +2,7 @@
  * SerialPort.java
  *
  *       Created on:  Feb 25, 2012
- *  Last Updated on:  Nov 12, 2021
+ *  Last Updated on:  Nov 19, 2021
  *           Author:  Will Hedgecock
  *
  * Copyright (C) 2012-2021 Fazecast, Inc.
@@ -417,6 +417,9 @@ public final class SerialPort
 	 * @return Whether the port was successfully opened with a valid configuration.
 	 */
 	public final synchronized boolean openPort(int safetySleepTime, int deviceSendQueueSize, int deviceReceiveQueueSize)
+	{
+		// Synchronize this method to the class scope as well
+        synchronized (SerialPort.class)
         {
 			// Set the send/receive internal buffer sizes, and return true if already opened
 			safetySleepTimeMS = safetySleepTime;
@@ -469,6 +472,7 @@ public final class SerialPort
 			}
 			return (portHandle > 0);
         }
+	}
 
 	/**
 	 * Opens this serial port for reading and writing with an optional delay time.
@@ -503,6 +507,9 @@ public final class SerialPort
 	 * @return Whether the port was successfully closed.
 	 */
 	public final synchronized boolean closePort()
+	{
+		// Synchronize this method to the class scope as well
+        synchronized (SerialPort.class)
         {
 			if (serialEventListener != null)
 				serialEventListener.stopListening();
@@ -510,6 +517,7 @@ public final class SerialPort
 				portHandle = closePortNative(portHandle);
 			return (portHandle < 0);
         }
+	}
 
 	/**
 	 * Returns whether the port is currently open and available for communication.