8274930: sun/tools/jps/TestJps.java can fail with long VM arguments s…

…tring

Reviewed-by: sspitsyn, lmesnik

test/jdk/sun/tools/jps/JpsHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -106,6 +106,7 @@ public static String[] asCmdArray(List<JpsArg> jpsArgs) {
     private static String[] testVmArgs = {
       "-XX:+UsePerfData", "-Xmx512m", "-Xlog:gc",
       "-Dmultiline.prop=value1\nvalue2\r\nvalue3",
+      "-XX:PerfMaxStringConstLength=8K",    // avoid VM flags truncations for "jps -v"
       null /* lazily initialized -XX:Flags */};
     private static File manifestFile = null;