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8141550: Introduce a command line option instead of nashorn.unstable.relink.threshold system property

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Reviewed-by: hannesw, sundar
This commit is contained in:
Attila Szegedi 2015-11-09 15:37:07 +01:00
parent e3ea5caf72
commit 75d6c996f1
9 changed files with 58 additions and 39 deletions
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18
nashorn/docs/DEVELOPER_README
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@ -35,12 +35,14 @@ that can be overwritten.
SYSTEM PROPERTY: -Dnashorn.unstable.relink.threshold=x
This property controls how many call site misses are allowed before a
callsite is relinked with "apply" semantics to never change again.
In the case of megamorphic callsites, this is necessary, or the
program would spend all its time swapping out callsite targets. Dynalink
has a default value (currently 8 relinks) for this property if it
is not explicitly set.
NOTE: This property is deprecated in favor of the
"--unstable-relink-threshold" command line option. It controls how many
call site misses are allowed before a callsite is relinked with "apply"
semantics to never change again. In the case of megamorphic callsites,
this is necessary, or the program would spend all its time swapping out
callsite targets. When neither the system property nor the command line
option are specified, defaults to 8, or 16 with optimistic types turned
on.
SYSTEM PROPERTY: -Dnashorn.compiler.splitter.threshold=x
@ -607,6 +609,10 @@ A short summary follows:
enterexit [trace callsite enter/exit], objects [print object properties].)
param: [=[option,]*]
-urt, --unstable-relink-threshold (Number of times a dynamic call site has to be relinked before it
is considered unstable, when the runtime will try to link it as
if it is megamorphic.)
--verify-code (Verify byte code before running.)
param: [true|false] default: false

2
nashorn/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/Context.java
View File

@ -649,7 +649,7 @@ public final class Context {
} else {
this.appLoader = appLoader;
}
this.dynamicLinker = Bootstrap.createDynamicLinker(this.appLoader);
this.dynamicLinker = Bootstrap.createDynamicLinker(this.appLoader, env._unstable_relink_threshold);
final int cacheSize = env._class_cache_size;
if (cacheSize > 0) {

25
nashorn/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/ScriptEnvironment.java
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@ -105,6 +105,12 @@ public final class ScriptEnvironment {
/** Enable experimental ECMAScript 6 features. */
public final boolean _es6;
/** Number of times a dynamic call site has to be relinked before it is
* considered unstable (and thus should be linked as if it were megamorphic).
*/
public final int _unstable_relink_threshold;
/** Argument passed to compile only if optimistic compilation should take place */
public static final String COMPILE_ONLY_OPTIMISTIC_ARG = "optimistic";
@ -287,6 +293,25 @@ public final class ScriptEnvironment {
_version = options.getBoolean("version");
_verify_code = options.getBoolean("verify.code");
final int configuredUrt = options.getInteger("unstable.relink.threshold");
// The default for this property is -1, so we can easily detect when
// it is not specified on command line.
if (configuredUrt < 0) {
// In this case, use a default of 8, or 16 for optimistic types.
// Optimistic types come with dual fields, and in order to get
// performance on benchmarks with a lot of object instantiation and
// then field reassignment, it can take slightly more relinks to
// become stable with type changes swapping out an entire property
// map and making a map guard fail. Also, honor the "nashorn.*"
// system property for now. It was documented in DEVELOPER_README
// so we should recognize it for the time being.
_unstable_relink_threshold = Options.getIntProperty(
"nashorn.unstable.relink.threshold",
_optimistic_types ? 16 : 8);
} else {
_unstable_relink_threshold = configuredUrt;
}
final String anonClasses = options.getString("anonymous.classes");
if (anonClasses == null || anonClasses.equals("auto")) {
_anonymousClasses = AnonymousClasses.AUTO;

28
nashorn/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/linker/Bootstrap.java
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@ -55,7 +55,6 @@ import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.OptimisticReturnFilters;
import jdk.nashorn.internal.runtime.ScriptFunction;
import jdk.nashorn.internal.runtime.ScriptRuntime;
import jdk.nashorn.internal.runtime.options.Options;
/**
* This class houses bootstrap method for invokedynamic instructions generated by compiler.
@ -68,25 +67,6 @@ public final class Bootstrap {
private static final MethodHandle VOID_TO_OBJECT = MH.constant(Object.class, ScriptRuntime.UNDEFINED);
/**
* The default dynalink relink threshold for megamorphism is 8. In the case
* of object fields only, it is fine. However, with dual fields, in order to get
* performance on benchmarks with a lot of object instantiation and then field
* reassignment, it can take slightly more relinks to become stable with type
* changes swapping out an entire property map and making a map guard fail.
* Since we need to set this value statically it must work with possibly changing
* optimistic types and dual fields settings. A higher value does not seem to have
* any other negative performance implication when running with object-only fields,
* so we choose a higher value here.
*
* See for example octane.gbemu, run with --log=fields:warning to study
* megamorphic behavior
*/
private static final int UNSTABLE_RELINK_THRESHOLD_DEFAULT = 16;
private static final int UNSTABLE_RELINK_THRESHOLD =
Options.getIntProperty("nashorn.unstable.relink.threshold",
UNSTABLE_RELINK_THRESHOLD_DEFAULT);
// do not create me!!
private Bootstrap() {
}
@ -95,9 +75,11 @@ public final class Bootstrap {
* Creates a Nashorn dynamic linker with the given app class loader.
* @param appLoader the app class loader. It will be used to discover
* additional language runtime linkers (if any).
* @param unstableRelinkThreshold the unstable relink threshold
* @return a newly created dynamic linker.
*/
public static DynamicLinker createDynamicLinker(final ClassLoader appLoader) {
public static DynamicLinker createDynamicLinker(final ClassLoader appLoader,
final int unstableRelinkThreshold) {
final DynamicLinkerFactory factory = new DynamicLinkerFactory();
final NashornBeansLinker nashornBeansLinker = new NashornBeansLinker();
factory.setPrioritizedLinkers(
@ -125,9 +107,7 @@ public final class Bootstrap {
}
});
factory.setInternalObjectsFilter(NashornBeansLinker.createHiddenObjectFilter());
if (UNSTABLE_RELINK_THRESHOLD > -1) {
factory.setUnstableRelinkThreshold(UNSTABLE_RELINK_THRESHOLD);
}
factory.setUnstableRelinkThreshold(unstableRelinkThreshold);
// Linkers for any additional language runtimes deployed alongside Nashorn will be picked up by the factory.
factory.setClassLoader(appLoader);

12
nashorn/src/jdk.scripting.nashorn/share/classes/jdk/nashorn/internal/runtime/resources/Options.properties
View File

@ -389,6 +389,18 @@ nashorn.option.anonymous.classes = { \
desc="Use VM anonymous classes for compiled scripts." \
}
nashorn.option.unstable.relink.threshold ={ \
name="--unstable-relink-threshold", \
short_name="-urt", \
desc="Number of times a dynamic call site has to be \
relinked before it is considered unstable, when the \
runtime will try to link it as if it is megamorphic.", \
is_undocumented=true, \
type=Integer, \
default=-1 \
}
nashorn.option.verify.code = { \
name="--verify-code", \
is_undocumented=true, \

3
nashorn/test/script/basic/JDK-8011578.js
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@ -25,8 +25,7 @@
* JDK-8011578 : -Dnashorn.unstable.relink.threshold=1 causes tests to fail.
*
* @test
* @option -Dnashorn.unstable.relink.threshold=1
* @fork
* @option --unstable-relink-threshold=1
* @run
*/

3
nashorn/test/script/basic/JDK-8044750.js
View File

@ -25,8 +25,7 @@
* JDK-8044750: megamorphic getter for scope objects does not call __noSuchProperty__ hook
*
* @test
* @fork
* @option -Dnashorn.unstable.relink.threshold=16
* @option --unstable-relink-threshold=16
* @run
*/

3
nashorn/test/script/basic/JDK-8136544.js
View File

@ -25,8 +25,7 @@
* JDK-8136544: Call site switching to megamorphic causes incorrect property read
*
* @test
* @fork
* @option -Dnashorn.unstable.relink.threshold=8
* @option --unstable-relink-threshold=8
* @run
*/

3
nashorn/test/script/basic/JDK-8136694.js
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@ -25,8 +25,7 @@
* JDK-8136694: Megemorphic scope access does not throw ReferenceError when property is missing
*
* @test
* @fork
* @option -Dnashorn.unstable.relink.threshold=16
* @option --unstable-relink-threshold=16
* @run
*/