gradle · oehme · Oct 18, 2018 · Oct 16, 2018
@@ -70,6 +70,11 @@ Here are the new features introduced in this Gradle release.
 IMPORTANT: if this is a patch release, ensure that a prominent link is included in the foreword to all releases of the same minor stream.
 Add-->
 
+### Starting Gradle as a lower priority process
+
+You can now use the `--priority low` command line argument or `org.gradle.priority=low` property to start Gradle as a low priority process.
+This ensures that other applications like your IDE or browser stay responsive, even while a very demanding build is running.
+
 ### Build init plugin improvements
 
 This release includes a number of improvements to The [Build Init plugin](userguide/build_init_plugin.html).

@@ -66,6 +66,8 @@ When configured, Gradle will fork up to `org.gradle.workers.max` JVMs to execute
 When set to `all`, `summary` or `none`, Gradle will use different warning type display. See <<command_line_interface.adoc#sec:command_line_logging,Command-line logging options>> for details.
 `org.gradle.workers.max=(max # of worker processes)`::
 When configured, Gradle will use a maximum of the given number of workers. Default is number of CPU processors. See also <<command_line_interface.adoc#sec:command_line_performance, performance command-line options>>.
+`org.gradle.priority=(low,normal)`::
+Specifies the scheduling priority for the Gradle daemon and all processes launched by it. Default is `normal`. See also <<command_line_interface.adoc#sec:command_line_performance, performance command-line options>>.
 
 The following example demonstrates usage of various properties.
 

@@ -340,6 +340,9 @@ Sets maximum number of workers that Gradle may use. _Default is number of proces
 `--parallel`, `--no-parallel`::
 Build projects in parallel. For limitations of this option, see <<multi_project_builds.adoc#sec:parallel_execution, Parallel Project Execution>>. _Default is off_.
 
+`--priority`::
+Specifies the scheduling priority for the Gradle daemon and all processes launched by it. Values are `normal` or `low`. _Default is normal_.
+
 `--profile`::
 Generates a high-level performance report in the `$buildDir/reports/profile` directory. `--scan` is preferred.
 

@@ -18,6 +18,7 @@
 
 import com.google.common.base.Splitter;
 import com.google.common.collect.Lists;
+import org.gradle.launcher.daemon.configuration.DaemonParameters;
 import org.gradle.launcher.daemon.context.DaemonContext;
 import org.gradle.launcher.daemon.context.DefaultDaemonContext;
 
@@ -57,7 +58,7 @@ public static DaemonContext parseFromString(String source) {
     }
 
     private static DaemonContext parseFrom(String source) {
-        Pattern pattern = Pattern.compile("^.*DefaultDaemonContext\\[(uid=[^\\n,]+)?,?javaHome=([^\\n]+),daemonRegistryDir=([^\\n]+),pid=([^\\n]+),idleTimeout=(.+?),daemonOpts=([^\\n]+)].*",
+        Pattern pattern = Pattern.compile("^.*DefaultDaemonContext\\[(uid=[^\\n,]+)?,?javaHome=([^\\n]+),daemonRegistryDir=([^\\n]+),pid=([^\\n]+),idleTimeout=(.+?)(,priority=[^\\n]+)?,daemonOpts=([^\\n]+)].*",
                 Pattern.MULTILINE + Pattern.DOTALL);
         Matcher matcher = pattern.matcher(source);
 
@@ -68,8 +69,9 @@ private static DaemonContext parseFrom(String source) {
             String pidStr = matcher.group(4);
             Long pid = pidStr.equals("null") ? null : Long.parseLong(pidStr);
             Integer idleTimeout = Integer.decode(matcher.group(5));
-            List<String> jvmOpts = Lists.newArrayList(Splitter.on(',').split(matcher.group(6)));
-            return new DefaultDaemonContext(uid, new File(javaHome), new File(daemonRegistryDir), pid, idleTimeout, jvmOpts);
+            DaemonParameters.Priority priority = matcher.group(6) == null ? DaemonParameters.Priority.NORMAL : DaemonParameters.Priority.valueOf(matcher.group(6).substring(",priority=".length()));
+            List<String> jvmOpts = Lists.newArrayList(Splitter.on(',').split(matcher.group(7)));
+            return new DefaultDaemonContext(uid, new File(javaHome), new File(daemonRegistryDir), pid, idleTimeout, jvmOpts, priority);
         } else {
             return null;
         }

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.gradle.launcher.daemon
+
+import org.gradle.integtests.fixtures.daemon.DaemonIntegrationSpec
+import org.gradle.internal.os.OperatingSystem
+
+class DaemonPriorityIntegrationTest extends DaemonIntegrationSpec {
+
+    /*
+     * Our command line length is already close to the limit of what Windows can handle.
+     * The few extra arguments that the priority change requires seem to push it over the edge.
+     * Using a distribution drastically shrinks the command line length, as the classpath is only
+     * one jar in that case.
+     */
+    def setup() {
+        if (OperatingSystem.current().isWindows()) {
+            requireGradleDistribution()
+        }
+    }
+
+    def "forks new daemon when priority is set to a different value via command line"() {
+        when:
+        run("help")
+
+        then:
+        daemons.daemons.size() == 1
+
+        when:
+        executer.withArguments("--priority", "low")
+        run("help")
+
+        then:
+        daemons.daemons.size() == 2
+    }
+
+    def "forks new daemon when priority is set to a different value via properties"() {
+        when:
+        run("help")
+
+        then:
+        daemons.daemons.size() == 1
+
+        when:
+        file("gradle.properties") << "org.gradle.priority=low"
+        run("help")
+
+        then:
+        daemons.daemons.size() == 2
+    }
+}
@@ -31,6 +31,7 @@
 import org.gradle.internal.service.scopes.GradleUserHomeScopeServiceRegistry;
 import org.gradle.launcher.bootstrap.EntryPoint;
 import org.gradle.launcher.bootstrap.ExecutionListener;
+import org.gradle.launcher.daemon.configuration.DaemonParameters;
 import org.gradle.launcher.daemon.configuration.DaemonServerConfiguration;
 import org.gradle.launcher.daemon.configuration.DefaultDaemonServerConfiguration;
 import org.gradle.launcher.daemon.context.DaemonContext;
@@ -79,6 +80,7 @@ protected void doAction(String[] args, ExecutionListener listener) {
         int periodicCheckIntervalMs;
         boolean singleUse;
         String daemonUid;
+        DaemonParameters.Priority priority;
         List<File> additionalClassPath;
 
         KryoBackedDecoder decoder = new KryoBackedDecoder(new EncodedStream.EncodedInput(System.in));
@@ -89,6 +91,7 @@ protected void doAction(String[] args, ExecutionListener listener) {
             periodicCheckIntervalMs = decoder.readSmallInt();
             singleUse = decoder.readBoolean();
             daemonUid = decoder.readString();
+            priority = DaemonParameters.Priority.values()[decoder.readSmallInt()];
             int argCount = decoder.readSmallInt();
             startupOpts = new ArrayList<String>(argCount);
             for (int i = 0; i < argCount; i++) {
@@ -104,7 +107,7 @@ protected void doAction(String[] args, ExecutionListener listener) {
         }
 
         NativeServices.initialize(gradleHomeDir);
-        DaemonServerConfiguration parameters = new DefaultDaemonServerConfiguration(daemonUid, daemonBaseDir, idleTimeoutMs, periodicCheckIntervalMs, singleUse, startupOpts);
+        DaemonServerConfiguration parameters = new DefaultDaemonServerConfiguration(daemonUid, daemonBaseDir, idleTimeoutMs, periodicCheckIntervalMs, singleUse, priority, startupOpts);
         LoggingServiceRegistry loggingRegistry = LoggingServiceRegistry.newCommandLineProcessLogging();
         LoggingManagerInternal loggingManager = loggingRegistry.newInstance(LoggingManagerInternal.class);
 

@@ -27,6 +27,7 @@
 import org.gradle.internal.installation.CurrentGradleInstallation;
 import org.gradle.internal.installation.GradleInstallation;
 import org.gradle.internal.io.StreamByteBuffer;
+import org.gradle.internal.os.OperatingSystem;
 import org.gradle.internal.serialize.FlushableEncoder;
 import org.gradle.internal.serialize.kryo.KryoBackedEncoder;
 import org.gradle.internal.time.Time;
@@ -48,6 +49,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.UUID;
@@ -93,6 +95,7 @@ public DaemonStartupInfo startDaemon(boolean singleUse) {
         versionValidator.validate(daemonParameters);
 
         List<String> daemonArgs = new ArrayList<String>();
+        daemonArgs.addAll(getPriorityArgs(daemonParameters.getPriority()));
         daemonArgs.add(daemonParameters.getEffectiveJvm().getJavaExecutable().getAbsolutePath());
 
         List<String> daemonOpts = daemonParameters.getEffectiveJvmArgs();
@@ -119,6 +122,7 @@ public DaemonStartupInfo startDaemon(boolean singleUse) {
             encoder.writeSmallInt(daemonParameters.getPeriodicCheckInterval());
             encoder.writeBoolean(singleUse);
             encoder.writeString(daemonUid);
+            encoder.writeSmallInt(daemonParameters.getPriority().ordinal());
             encoder.writeSmallInt(daemonOpts.size());
             for (String daemonOpt : daemonOpts) {
                 encoder.writeString(daemonOpt);
@@ -136,6 +140,20 @@ public DaemonStartupInfo startDaemon(boolean singleUse) {
         return startProcess(daemonArgs, daemonDir.getVersionedDir(), stdInput);
     }
 
+    private List<String> getPriorityArgs(DaemonParameters.Priority priority) {
+        if (priority == DaemonParameters.Priority.NORMAL) {
+            return Collections.emptyList();
+        }
+        OperatingSystem os = OperatingSystem.current();
+        if (os.isUnix()) {
+            return Arrays.asList("nice", "-n", "10");
+        } else if (os.isWindows()) {
+            return Arrays.asList("cmd", "/C", "start", "\"Gradle build daemon\"", "/B", "/belownormal", "/WAIT");
+        } else {
+            return Collections.emptyList();
+        }
+    }
+
     private DaemonStartupInfo startProcess(List<String> args, File workingDir, InputStream stdInput) {
         LOGGER.debug("Starting daemon process: workingDir = {}, daemonArgs: {}", workingDir, args);
         Timer clock = Time.startTimer();

@@ -32,6 +32,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 
 public class DaemonBuildOptions {
 
@@ -49,6 +50,7 @@ public class DaemonBuildOptions {
         options.add(new ForegroundOption());
         options.add(new StopOption());
         options.add(new StatusOption());
+        options.add(new PriorityOption());
         DaemonBuildOptions.options = Collections.unmodifiableList(options);
     }
 
@@ -201,4 +203,21 @@ public void applyTo(DaemonParameters settings, Origin origin) {
             settings.setStatus(true);
         }
     }
+
+    public static class PriorityOption extends StringBuildOption<DaemonParameters> {
+        public static final String GRADLE_PROPERTY = "org.gradle.priority";
+
+        public PriorityOption() {
+            super(GRADLE_PROPERTY, CommandLineOptionConfiguration.create("priority", "Specifies the scheduling priority for the Gradle daemon and all processes launched by it. Values are 'normal' (default) or 'low'").incubating());
+        }
+
+        @Override
+        public void applyTo(String value, DaemonParameters settings, Origin origin) {
+            try {
+                settings.setPriority(DaemonParameters.Priority.valueOf(value.toUpperCase(Locale.ROOT)));
+            } catch (IllegalArgumentException e) {
+                origin.handleInvalidValue(value);
+            }
+        }
+    }
 }
@@ -53,6 +53,7 @@ public class DaemonParameters {
     private boolean foreground;
     private boolean stop;
     private boolean status;
+    private Priority priority = Priority.NORMAL;
     private JavaInfo jvm = Jvm.current();
 
     public DaemonParameters(BuildLayoutParameters layout) {
@@ -207,4 +208,17 @@ public void setStatus(boolean status) {
     public Map<String, String> getEnvironmentVariables() {
         return envVariables;
     }
+
+    public Priority getPriority() {
+        return priority;
+    }
+
+    public void setPriority(Priority priority) {
+        this.priority = priority;
+    }
+
+    public enum Priority {
+        LOW,
+        NORMAL,
+    }
 }
@@ -31,5 +31,7 @@ public interface DaemonServerConfiguration {
 
     List<String> getJvmOptions();
 
+    DaemonParameters.Priority getPriority();
+
     boolean isSingleUse();
 }
@@ -26,14 +26,16 @@ public class DefaultDaemonServerConfiguration implements DaemonServerConfigurati
     private final int idleTimeoutMs;
     private final int periodicCheckIntervalMs;
     private final boolean singleUse;
+    private final DaemonParameters.Priority priority;
     private final List<String> jvmOptions;
 
-    public DefaultDaemonServerConfiguration(String daemonUid, File daemonBaseDir, int idleTimeoutMs, int periodicCheckIntervalMs, boolean singleUse, List<String> jvmOptions) {
+    public DefaultDaemonServerConfiguration(String daemonUid, File daemonBaseDir, int idleTimeoutMs, int periodicCheckIntervalMs, boolean singleUse, DaemonParameters.Priority priority, List<String> jvmOptions) {
         this.daemonUid = daemonUid;
         this.daemonBaseDir = daemonBaseDir;
         this.idleTimeoutMs = idleTimeoutMs;
         this.periodicCheckIntervalMs = periodicCheckIntervalMs;
         this.singleUse = singleUse;
+        this.priority = priority;
         this.jvmOptions = jvmOptions;
     }
 
@@ -57,6 +59,10 @@ public String getUid() {
         return daemonUid;
     }
 
+    public DaemonParameters.Priority getPriority() {
+        return priority;
+    }
+
     @Override
     public List<String> getJvmOptions() {
         return jvmOptions;

@@ -23,6 +23,6 @@
 public class ForegroundDaemonConfiguration extends DefaultDaemonServerConfiguration {
     public ForegroundDaemonConfiguration(String daemonUid, File daemonBaseDir, int idleTimeoutMs, int periodicCheckIntervalMs) {
         // Foreground daemon cannot be 'told' what's his startup options as the client sits in the same process so we will infer the jvm opts from the inputArguments()
-        super(daemonUid, daemonBaseDir, idleTimeoutMs, periodicCheckIntervalMs, false, new CurrentProcess().getJvmOptions().getAllImmutableJvmArgs());
+        super(daemonUid, daemonBaseDir, idleTimeoutMs, periodicCheckIntervalMs, false, DaemonParameters.Priority.NORMAL, new CurrentProcess().getJvmOptions().getAllImmutableJvmArgs());
     }
 }
@@ -36,26 +36,32 @@ public String whyUnsatisfied(DaemonContext context) {
             return "Java home is different.\n" + description(context);
         } else if (!daemonOptsMatch(context)) {
             return "At least one daemon option is different.\n" + description(context);
+        } else if (!priorityMatches(context)) {
+            return "Process priority is different.\n" + description(context);
         }
         return null;
     }
 
     private String description(DaemonContext context) {
         return "Wanted: " + this + "\n"
-                + "Actual: " + context + "\n";
+            + "Actual: " + context + "\n";
     }
 
     private boolean daemonOptsMatch(DaemonContext potentialContext) {
         return potentialContext.getDaemonOpts().containsAll(desiredContext.getDaemonOpts())
-                && potentialContext.getDaemonOpts().size() == desiredContext.getDaemonOpts().size();
+            && potentialContext.getDaemonOpts().size() == desiredContext.getDaemonOpts().size();
     }
 
     private boolean javaHomeMatches(DaemonContext potentialContext) {
         return canonicalize(potentialContext.getJavaHome()).equals(canonicalize(desiredContext.getJavaHome()));
     }
 
+    private boolean priorityMatches(DaemonContext context) {
+        return desiredContext.getPriority() == context.getPriority();
+    }
+
     @Override
     public String toString() {
         return desiredContext.toString();
     }
-}
+}
@@ -15,6 +15,8 @@
  */
 package org.gradle.launcher.daemon.context;
 
+import org.gradle.launcher.daemon.configuration.DaemonParameters;
+
 import java.io.File;
 import java.io.Serializable;
 import java.util.List;
@@ -65,4 +67,6 @@ public interface DaemonContext extends Serializable {
      * @return the JVM options that the daemon was started with
      */
     List<String> getDaemonOpts();
-}
+
+    DaemonParameters.Priority getPriority();
+}