Issue

We observed high CPU consumption on our server, and from TOP command we identified the high CPU Java threads. From thread dump we see those threads are in loop to solve Java regular expressions.

From thread dump we see below stack trace:-

 http-X.X.X.X-YYYY-Z" daemon prio=10 tid=0x0000000052e7a800 nid=0x1352 runnable [0x0000000045f72000]
      java.lang.Thread.State: RUNNABLE
      at java.util.regex.Pattern$GroupTail.match(Pattern.java:4227)
      at java.util.regex.Pattern$BranchConn.match(Pattern.java:4078)
      at java.util.regex.Pattern$GroupTail.match(Pattern.java:4227)
      at java.util.regex.Pattern$Branch.match(Pattern.java:4112)
      at java.util.regex.Pattern$GroupHead.match(Pattern.java:4168)
      at java.util.regex.Pattern$Branch.match(Pattern.java:4114)
      at java.util.regex.Pattern$GroupHead.match(Pattern.java:4168)
      at java.util.regex.Pattern$Loop.match(Pattern.java:4295)
      ... continues 
      at java.util.regex.Pattern$BranchConn.match(Pattern.java:4078)
      at java.util.regex.Pattern$CharProperty.match(Pattern.java:3345)
      at java.util.regex.Pattern$Branch.match(Pattern.java:4114)
      at java.util.regex.Pattern$GroupHead.match(Pattern.java:4168)
      at java.util.regex.Pattern$Loop.matchInit(Pattern.java:4314)
      at java.util.regex.Pattern$Prolog.match(Pattern.java:4251)
      at java.util.regex.Matcher.match(Matcher.java:1127)
      at java.util.regex.Matcher.matches(Matcher.java:502)
      at java.util.regex.Pattern.matches(Pattern.java:930)
      at java.lang.String.matches(String.java:2090)
      at xx.yyy.zzz.xyzValid()