Try to fix linux pdf opening again

src/main/java/org/jabref/gui/desktop/os/Linux.java

@@ -11,8 +11,10 @@
 import java.util.Optional;
 import java.util.StringJoiner;
 
+import org.jabref.JabRefExecutorService;
 import org.jabref.gui.externalfiletype.ExternalFileType;
 import org.jabref.gui.externalfiletype.ExternalFileTypes;
+import org.jabref.gui.util.StreamGobbler;
 import org.jabref.preferences.JabRefPreferences;
 
 import org.slf4j.Logger;
@@ -22,6 +24,7 @@
 import static org.jabref.preferences.JabRefPreferences.USE_PDF_READER;
 
 public class Linux implements NativeDesktop {
+
     private static final Logger LOGGER = LoggerFactory.getLogger(Linux.class);
 
     @Override
@@ -34,7 +37,7 @@ public void openFile(String filePath, String fileType) throws IOException {
         } else {
             viewer = "xdg-open";
         }
-        String[] cmdArray = { viewer, filePath };
+        String[] cmdArray = {viewer, filePath};
         Process p = Runtime.getRuntime().exec(cmdArray);
         // When the stream is full at some point, then blocks the execution of the program
         // See https://stackoverflow.com/questions/10981969/why-is-going-through-geterrorstream-necessary-to-run-a-process.
@@ -53,17 +56,18 @@ public void openFileWithApplication(String filePath, String application) throws
         } else {
             openWith = new String[] {"xdg-open"};
         }
-
         String[] cmdArray = new String[openWith.length + 1];
         System.arraycopy(openWith, 0, cmdArray, 0, openWith.length);
         cmdArray[cmdArray.length - 1] = filePath;
-        Process p = Runtime.getRuntime().exec(cmdArray);
+
+        Process process = Runtime.getRuntime().exec(cmdArray);
         // When the stream is full at some point, then blocks the execution of the program
         // See https://stackoverflow.com/questions/10981969/why-is-going-through-geterrorstream-necessary-to-run-a-process.
-        BufferedReader in = new BufferedReader(new InputStreamReader(p.getErrorStream()));
-        String line;
-        line = in.readLine();
-        LOGGER.debug("Received output: " + line);
+        StreamGobbler streamGobblerInput = new StreamGobbler(process.getInputStream(), LOGGER::debug);
+        StreamGobbler streamGobblerError = new StreamGobbler(process.getErrorStream(), LOGGER::debug);
+
+        JabRefExecutorService.INSTANCE.execute(streamGobblerInput);
+        JabRefExecutorService.INSTANCE.execute(streamGobblerError);
     }
 
     @Override
@@ -118,7 +122,7 @@ public void openPdfWithParameters(String filePath, List<String> parameters) thro
 
             openFileWithApplication(filePath, sj.toString());
         } else {
-            openFile( filePath, "PDF");
+            openFile(filePath, "PDF");
         }
     }
 

src/main/java/org/jabref/gui/util/StreamGobbler.java

@@ -0,0 +1,22 @@
+package org.jabref.gui.util;
+
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.function.Consumer;
+
+public class StreamGobbler implements Runnable {
+
+    private InputStream inputStream;
+    private Consumer<String> consumer;
+
+    public StreamGobbler(InputStream inputStream, Consumer<String> consumer) {
+        this.inputStream = inputStream;
+        this.consumer = consumer;
+    }
+
+    @Override
+    public void run() {
+        new BufferedReader(new InputStreamReader(inputStream)).lines().forEach(consumer);
+    }
+}