MSC01-J. Do not use an empty infinite loop

An infinite loop with an empty body is a suboptimal solution because it consumes CPU cycles but does nothing. Optimizing compilers and JITs are permitted to remove such a loop, which can lead to unexpected results. Consequently, programs must not include infinite loops with empty bodies.

Noncompliant Code Example

This noncompliant code example implements an idle task that continuously executes a loop without executing any instructions within the loop. An optimizing compiler or JIT could remove the while loop in the example.

public int nop() {
  while (true) {}
}

Compliant Solution (Thread.sleep())

This compliant solution avoids use of a meaningless infinite loop by sleeping the current thread within the while loop. The loop body contains semantically meaningful operations and consequently cannot be optimized away.

public final int DURATION=10000; // in milliseconds

public void nop() throws InterruptedException {
  while (true) {
    Thread.sleep(DURATION);
  }
}

Compliant Solution (yield())

This compliant solution invokes Thread.yield(), which causes the thread running this method to consistently defer to other threads.

public void nop() {
  while (true) {
    Thread.yield();
  }
}

Risk Assessment

Related Guidelines

Bibliography

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