Package org.apache.druid.utils

Class JvmUtils

java.lang.Object

org.apache.druid.utils.JvmUtils

public class JvmUtils
extends Object

Field Summary

Fields

Modifier and Type	Field	Description
static int	UNKNOWN_VERSION

Constructor Summary

Constructors

Constructor	Description
JvmUtils()

Method Summary

Modifier and Type	Method	Description
static long	getCurrentThreadCpuTime()	Returns the total CPU time for current thread.
static RuntimeInfo	getRuntimeInfo()
static boolean	isIsJava9Compatible()
static boolean	isThreadCpuTimeEnabled()
static int	majorVersion()	Returns the major version of the current Java runtime for Java 9 and above.
static void	resetTestsToDefaultRuntimeInfo()	Only for testing.
static <T> T	safeAccumulateThreadCpuTime(AtomicLong accumulator, Supplier<T> function)	Executes and returns the value of function.
static long	safeGetThreadCpuTime()
static List<URL>	systemClassPath()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

UNKNOWN_VERSION

public static final int UNKNOWN_VERSION

See Also:

Constant Field Values

Constructor Detail

JvmUtils

public JvmUtils()

Method Detail

majorVersion

public static int majorVersion()

Returns the major version of the current Java runtime for Java 9 and above. For example: 9, 11, 17, etc. Returns 1 for Java 8 and earlier. Returns UNKNOWN_VERSION if the major version cannot be determined. This is a negative number and is therefore lower than all valid versions.

isIsJava9Compatible

public static boolean isIsJava9Compatible()

getRuntimeInfo

public static RuntimeInfo getRuntimeInfo()

isThreadCpuTimeEnabled

public static boolean isThreadCpuTimeEnabled()

safeGetThreadCpuTime

public static long safeGetThreadCpuTime()

getCurrentThreadCpuTime

public static long getCurrentThreadCpuTime()

Returns the total CPU time for current thread. This method should be called after verifying that cpu time measurement for current thread is supported by JVM

Returns:

total CPU time for the current thread in nanoseconds.

Throws:

UnsupportedOperationException - if the Java virtual machine does not support CPU time measurement for the current thread.

safeAccumulateThreadCpuTime

public static <T> T safeAccumulateThreadCpuTime(AtomicLong accumulator,
                                                Supplier<T> function)

Executes and returns the value of function. Also accumulates the CPU time taken for the function (as reported by getCurrentThreadCpuTime() into {@param accumulator}.

systemClassPath

public static List<URL> systemClassPath()

resetTestsToDefaultRuntimeInfo

public static void resetTestsToDefaultRuntimeInfo()

Only for testing.