Use simple patterns to parse cgroup files

Author: pejovica

src/java.base/linux/classes/jdk/internal/platform/CgroupInfo.java

@@ -107,7 +107,7 @@ public void setCgroupPath(String cgroupPath) {
      *
      */
     static CgroupInfo fromCgroupsLine(String line) {
-        String[] tokens = line.split("\\s+");
+        String[] tokens = line.split("\t");
         if (tokens.length != 4) {
             return null;
         }

src/java.base/linux/classes/jdk/internal/platform/cgroupv1/CgroupV1SubsystemController.java

@@ -107,7 +107,7 @@ public static long getLongValueMatchingLine(CgroupSubsystemController controller
     }
 
     public static long convertHierachicalLimitLine(String line) {
-        String[] tokens = line.split("\\s");
+        String[] tokens = line.split(" ");
         if (tokens.length == 2) {
             String strVal = tokens[1];
             return CgroupV1SubsystemController.convertStringToLong(strVal);

src/java.base/linux/classes/jdk/internal/platform/cgroupv2/CgroupV2Subsystem.java

@@ -143,7 +143,7 @@ private long getFromCpuMax(int tokenIdx) {
             return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
         }
         // $MAX $PERIOD
-        String[] tokens = cpuMaxRaw.split("\\s+");
+        String[] tokens = cpuMaxRaw.split(" ");
         if (tokens.length != 2) {
             return CgroupSubsystem.LONG_RETVAL_UNLIMITED;
         }
@@ -359,7 +359,7 @@ private static Long ioStatLineToLong(String line, String[] matchNames) {
         if (line == null || EMPTY_STR.equals(line)) {
             return Long.valueOf(0);
         }
-        String[] tokens = line.split("\\s+");
+        String[] tokens = line.split(" ");
         long retval = 0;
         for (String t: tokens) {
             String[] valKeys = t.split("=");