To run dex in process, the Gradle daemon needs a larger heap. It currently has approximately 910 MB

I am getting this Gradle error every time I run my app. The error is:

To run dex in process, the Gradle daemon needs a larger heap. It currently has approximately 910 MB.

For faster builds, increase the maximum heap size for the Gradle daemon to more than 2048 MB.

To do this set org.gradle.jvmargs=-Xmx2048M in the project gradle.properties. For more information see https://docs.gradle.org/current/userguide/build_environment.html

Here is my build.gradle (Module:app) file:

apply plugin: 'com.android.application'

    android {
        compileSdkVersion 23
        buildToolsVersion "23.0.3"

        defaultConfig {
            applicationId "mobileapp.tech2dsk"
            minSdkVersion 15
            targetSdkVersion 23
            versionCode 1
            versionName "1.0"
        }
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            }
        }
    }

    dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        testCompile 'junit:junit:4.12'
        compile 'com.android.support:appcompat-v7:23.3.0'
        compile 'com.android.support:design:23.3.0'
    }

And here is my build.gradle(Project) file:

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.1.0'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

and here is my gradle.properties file :

# Project-wide Gradle settings.

# IDE (e.g. Android Studio) users:
# Gradle settings configured through the IDE *will override*
# any settings specified in this file.

# For more details on how to configure your build environment visit
# http://www.gradle.org/docs/current/userguide/build_environment.html

# Specifies the JVM arguments used for the daemon process.
# The setting is particularly useful for tweaking memory settings.
# Default value: -Xmx10248m -XX:MaxPermSize=256m
# org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

# When configured, Gradle will run in incubating parallel mode.
# This option should only be used with decoupled projects. More details, visit
# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
# org.gradle.parallel=true

Update from June 25, 2017

At Google IO 2017 there was some updates about this topic. It's not recommended anymore to set the flag on the dexOptions, so if you have something like the next, you can delete it.

dexOptions {
   javaMaxHeapSize "2g"
}

• Source: Speeding Up Your Android Gradle Builds

Original answer:

Android Studio 2.1 enables Dex In Process which shares the VM with Gradle to improve build times. Due to this, it's necessary to increase the size of the Gradle daemon to incorporate those Dex processes.

At least it's necessary 2 gigs of memory, but you can try with three if you can afford it.

gradle.properties.

org.gradle.jvmargs=-Xmx3072m

By default the Java max heap size is one gig, but in case you have modified it on the build.gradle file...

build.gradle (App)

dexOptions {
   javaMaxHeapSize "2g"
}

...you have to resize the Gradle daemon size accordingly (has to be bigger to fit the heap).

• Resources

  1. Official blog post by Reto Meier
  2. Official Video in Android Developers
  3. DexOptions docs.

Notes:

• Please realize above numbers varies from machine to machine.

Add in your Build.gradle

android {
 dexOptions {
    javaMaxHeapSize "4g"
  }
}

More info - Android Gradle: What is javaMaxHeapSize "4g"?