Hello,
while investigating an issue I've found out that assignment of default value to
volatile fields slows down object instantiation.
Consider the benchmark:
@State(Scope.Thread)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@BenchmarkMode(value = Mode.AverageTime)
@Fork(jvmArgsAppend = {"-Xms2g", "-Xmx2g"})
public class VolatileFieldBenchmark {
@Benchmark
public Object explicitInit() {
return new ExplicitInit();
}
@Benchmark
public Object noInit() {
return new NoInit();
}
private static class ExplicitInit {
private volatile boolean field = false;
}
private static class NoInit {
private volatile boolean field;
}
}
This gives the following results as of my machine:
Benchmark Mode Cnt Score Error Units
VolatileFieldBenchmark.explicitInit avgt 40 11.087 ± 0.140 ns/op
VolatileFieldBenchmark.noInit avgt 40 3.367 ± 0.131 ns/op
I've looked into source code of java.base and found out several cases where the
default value is assigned to volatile field.
Getting rid of such assignements demonstates improvement as of object
instantiation, e.g. javax.security.auth.Subject:
Mode Cnt Score Error Units
before avgt 40 35.933 ± 2.647 ns/op
after avgt 40 30.817 ± 2.384 ns/op
As of testing tier1 and tier2 are both ok after the changes.
Best regards,
Sergey Tsypanovdiff --git a/src/java.base/share/classes/java/security/KeyStore.java b/src/java.base/share/classes/java/security/KeyStore.java
--- a/src/java.base/share/classes/java/security/KeyStore.java
+++ b/src/java.base/share/classes/java/security/KeyStore.java
@@ -219,7 +219,7 @@
private KeyStoreSpi keyStoreSpi;
// Has this keystore been initialized (loaded)?
- private boolean initialized = false;
+ private boolean initialized;
/**
* A marker interface for {@code KeyStore}
@@ -264,7 +264,7 @@
private final char[] password;
private final String protectionAlgorithm;
private final AlgorithmParameterSpec protectionParameters;
- private volatile boolean destroyed = false;
+ private volatile boolean destroyed;
/**
* Creates a password parameter.
diff --git a/src/java.base/share/classes/java/util/ListResourceBundle.java b/src/java.base/share/classes/java/util/ListResourceBundle.java
--- a/src/java.base/share/classes/java/util/ListResourceBundle.java
+++ b/src/java.base/share/classes/java/util/ListResourceBundle.java
@@ -206,5 +206,5 @@
lookup = temp;
}
- private volatile Map<String,Object> lookup = null;
+ private volatile Map<String,Object> lookup;
}
diff --git a/src/java.base/share/classes/javax/security/auth/Subject.java b/src/java.base/share/classes/javax/security/auth/Subject.java
--- a/src/java.base/share/classes/javax/security/auth/Subject.java
+++ b/src/java.base/share/classes/javax/security/auth/Subject.java
@@ -126,7 +126,7 @@
*
* @serial
*/
- private volatile boolean readOnly = false;
+ private volatile boolean readOnly;
private static final int PRINCIPAL_SET = 1;
private static final int PUB_CREDENTIAL_SET = 2;
diff --git a/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java b/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java
--- a/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java
+++ b/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java
@@ -71,7 +71,7 @@
// Common working status
- private boolean instantiated = false;
+ private boolean instantiated;
/**
* Reseed counter of a DRBG instance. A mechanism should increment it
@@ -80,7 +80,7 @@
*
* Volatile, will be used in a double checked locking.
*/
- protected volatile int reseedCounter = 0;
+ protected volatile int reseedCounter;
// Mech features. If not same as below, must be redefined in constructor.
diff --git a/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java b/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java
--- a/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java
+++ b/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java
@@ -36,7 +36,7 @@
*/
final class DTLSOutputRecord extends OutputRecord implements DTLSRecord {
- private DTLSFragmenter fragmenter = null;
+ private DTLSFragmenter fragmenter;
int writeEpoch;
@@ -44,7 +44,7 @@
Authenticator prevWriteAuthenticator;
SSLWriteCipher prevWriteCipher;
- private volatile boolean isCloseWaiting = false;
+ private volatile boolean isCloseWaiting;
DTLSOutputRecord(HandshakeHash handshakeHash) {
super(handshakeHash, SSLWriteCipher.nullDTlsWriteCipher());
diff --git a/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java b/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java
--- a/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java
+++ b/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java
@@ -102,11 +102,11 @@
boolean isResumption;
SSLSessionImpl resumingSession;
// Session is using stateless resumption
- boolean statelessResumption = false;
+ boolean statelessResumption;
final Queue<Map.Entry<Byte, ByteBuffer>> delegatedActions;
- volatile boolean taskDelegated = false;
- volatile Exception delegatedThrown = null;
+ volatile boolean taskDelegated;
+ volatile Exception delegatedThrown;
ProtocolVersion negotiatedProtocol;
CipherSuite negotiatedCipherSuite;
diff --git a/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java b/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java
--- a/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java
+++ b/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java
@@ -37,11 +37,11 @@
*/
final class SSLEngineOutputRecord extends OutputRecord implements SSLRecord {
- private HandshakeFragment fragmenter = null;
- private boolean isTalkingToV2 = false; // SSLv2Hello
- private ByteBuffer v2ClientHello = null; // SSLv2Hello
+ private HandshakeFragment fragmenter;
+ private boolean isTalkingToV2; // SSLv2Hello
+ private ByteBuffer v2ClientHello; // SSLv2Hello
- private volatile boolean isCloseWaiting = false;
+ private volatile boolean isCloseWaiting;
SSLEngineOutputRecord(HandshakeHash handshakeHash) {
super(handshakeHash, SSLWriteCipher.nullTlsWriteCipher());
diff --git a/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java b/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
--- a/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
+++ b/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
@@ -83,8 +83,8 @@
private String peerHost;
private boolean autoClose;
- private boolean isConnected = false;
- private volatile boolean tlsIsClosed = false;
+ private boolean isConnected;
+ private volatile boolean tlsIsClosed;
private final ReentrantLock socketLock = new ReentrantLock();
private final ReentrantLock handshakeLock = new ReentrantLock();
--- Begin Message ---
Hello,
while investigating an issue I've found out that assignment of default value to
volatile fields slows down object instantiation.
Consider the benchmark:
@State(Scope.Thread)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@BenchmarkMode(value = Mode.AverageTime)
@Fork(jvmArgsAppend = {"-Xms2g", "-Xmx2g"})
public class VolatileFieldBenchmark {
@Benchmark
public Object explicitInit() {
return new ExplicitInit();
}
@Benchmark
public Object noInit() {
return new NoInit();
}
private static class ExplicitInit {
private volatile boolean field = false;
}
private static class NoInit {
private volatile boolean field;
}
}
This gives the following results as of my machine:
Benchmark Mode Cnt Score Error Units
VolatileFieldBenchmark.explicitInit avgt 40 11.087 ± 0.140 ns/op
VolatileFieldBenchmark.noInit avgt 40 3.367 ± 0.131 ns/op
I've looked into source code of java.base and found out several cases where the
default value is assigned to volatile field.
Getting rid of such assignements demonstates improvement as of object
instantiation, e.g. javax.security.auth.Subject:
Mode Cnt Score Error Units
before avgt 40 35.933 ± 2.647 ns/op
after avgt 40 30.817 ± 2.384 ns/op
As of testing tier1 and tier2 are both ok after the changes.
Best regards,
Sergey Tsypanovdiff --git a/src/java.base/share/classes/java/security/KeyStore.java b/src/java.base/share/classes/java/security/KeyStore.java
--- a/src/java.base/share/classes/java/security/KeyStore.java
+++ b/src/java.base/share/classes/java/security/KeyStore.java
@@ -219,7 +219,7 @@
private KeyStoreSpi keyStoreSpi;
// Has this keystore been initialized (loaded)?
- private boolean initialized = false;
+ private boolean initialized;
/**
* A marker interface for {@code KeyStore}
@@ -264,7 +264,7 @@
private final char[] password;
private final String protectionAlgorithm;
private final AlgorithmParameterSpec protectionParameters;
- private volatile boolean destroyed = false;
+ private volatile boolean destroyed;
/**
* Creates a password parameter.
diff --git a/src/java.base/share/classes/java/util/ListResourceBundle.java b/src/java.base/share/classes/java/util/ListResourceBundle.java
--- a/src/java.base/share/classes/java/util/ListResourceBundle.java
+++ b/src/java.base/share/classes/java/util/ListResourceBundle.java
@@ -206,5 +206,5 @@
lookup = temp;
}
- private volatile Map<String,Object> lookup = null;
+ private volatile Map<String,Object> lookup;
}
diff --git a/src/java.base/share/classes/javax/security/auth/Subject.java b/src/java.base/share/classes/javax/security/auth/Subject.java
--- a/src/java.base/share/classes/javax/security/auth/Subject.java
+++ b/src/java.base/share/classes/javax/security/auth/Subject.java
@@ -126,7 +126,7 @@
*
* @serial
*/
- private volatile boolean readOnly = false;
+ private volatile boolean readOnly;
private static final int PRINCIPAL_SET = 1;
private static final int PUB_CREDENTIAL_SET = 2;
diff --git a/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java b/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java
--- a/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java
+++ b/src/java.base/share/classes/sun/security/provider/AbstractDrbg.java
@@ -71,7 +71,7 @@
// Common working status
- private boolean instantiated = false;
+ private boolean instantiated;
/**
* Reseed counter of a DRBG instance. A mechanism should increment it
@@ -80,7 +80,7 @@
*
* Volatile, will be used in a double checked locking.
*/
- protected volatile int reseedCounter = 0;
+ protected volatile int reseedCounter;
// Mech features. If not same as below, must be redefined in constructor.
diff --git a/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java b/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java
--- a/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java
+++ b/src/java.base/share/classes/sun/security/ssl/DTLSOutputRecord.java
@@ -36,7 +36,7 @@
*/
final class DTLSOutputRecord extends OutputRecord implements DTLSRecord {
- private DTLSFragmenter fragmenter = null;
+ private DTLSFragmenter fragmenter;
int writeEpoch;
@@ -44,7 +44,7 @@
Authenticator prevWriteAuthenticator;
SSLWriteCipher prevWriteCipher;
- private volatile boolean isCloseWaiting = false;
+ private volatile boolean isCloseWaiting;
DTLSOutputRecord(HandshakeHash handshakeHash) {
super(handshakeHash, SSLWriteCipher.nullDTlsWriteCipher());
diff --git a/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java b/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java
--- a/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java
+++ b/src/java.base/share/classes/sun/security/ssl/HandshakeContext.java
@@ -102,11 +102,11 @@
boolean isResumption;
SSLSessionImpl resumingSession;
// Session is using stateless resumption
- boolean statelessResumption = false;
+ boolean statelessResumption;
final Queue<Map.Entry<Byte, ByteBuffer>> delegatedActions;
- volatile boolean taskDelegated = false;
- volatile Exception delegatedThrown = null;
+ volatile boolean taskDelegated;
+ volatile Exception delegatedThrown;
ProtocolVersion negotiatedProtocol;
CipherSuite negotiatedCipherSuite;
diff --git a/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java b/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java
--- a/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java
+++ b/src/java.base/share/classes/sun/security/ssl/SSLEngineOutputRecord.java
@@ -37,11 +37,11 @@
*/
final class SSLEngineOutputRecord extends OutputRecord implements SSLRecord {
- private HandshakeFragment fragmenter = null;
- private boolean isTalkingToV2 = false; // SSLv2Hello
- private ByteBuffer v2ClientHello = null; // SSLv2Hello
+ private HandshakeFragment fragmenter;
+ private boolean isTalkingToV2; // SSLv2Hello
+ private ByteBuffer v2ClientHello; // SSLv2Hello
- private volatile boolean isCloseWaiting = false;
+ private volatile boolean isCloseWaiting;
SSLEngineOutputRecord(HandshakeHash handshakeHash) {
super(handshakeHash, SSLWriteCipher.nullTlsWriteCipher());
diff --git a/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java b/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
--- a/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
+++ b/src/java.base/share/classes/sun/security/ssl/SSLSocketImpl.java
@@ -83,8 +83,8 @@
private String peerHost;
private boolean autoClose;
- private boolean isConnected = false;
- private volatile boolean tlsIsClosed = false;
+ private boolean isConnected;
+ private volatile boolean tlsIsClosed;
private final ReentrantLock socketLock = new ReentrantLock();
private final ReentrantLock handshakeLock = new ReentrantLock();
--- End Message ---
