Method and apparatus for determining frequency of execution for compiled methods within a virtual machine

A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for determining a relative frequency of execution of compiled methods within a virtual machine, the method comprising:

• a flag array wherein each compiled method has a corresponding index into the flag array;
• wherein each compiled method has a corresponding counter;
• when a compiled method is executed, setting a flag in the flag array corresponding to the compiled method to indicate that the compiled method is executing;
• periodically, scanning the flag array and for each compiled method, incrementing a value of the corresponding counter if the flag corresponding to the compiled method is set to indicate that the compiled method has executed at least once since the flag array was last reset, and then resetting the flag array for subsequent scanning;
• and
• for each compiled method, analyzing the value of the corresponding counter to determine a relative frequency of execution of each of the compiled methods.

An apparatus for determining a relative frequency of execution of compiled methods within a virtual machine, comprising:

• a processor;
• a memory;
• a flag array wherein each compiled method has a corresponding index into the flag array;
• wherein each compiled method has a corresponding counter;
• a determination mechanism configured to determine when a compiled method is executed;
• a flag setting mechanism configured to set a flag in the flag array corresponding to the compiled method to indicate that the compiled method is executing, if the compiled method is executing;
• a scanning mechanism configured to periodically scan the flag array and for each compiled method, increment a value of the corresponding counter if the flag corresponding to the compiled method is set to indicate that the compiled method has executed at least once since the flag array was last reset, and to reset the flag array for subsequent scanning;
• and
• an analysis mechanism configured to analyze the value of the corresponding counter for each compiled method to determine a relative frequency of execution of each of the compiled methods.