Why does appengine try to use Super Dev Mode?
Every time I deploy my GWT app to appengine and try to access it I get the white loading screen, then after about 20-30 seconds I get this message:
I use maven with the gwt-maven-plugin and appengine-maven-plugin. Deploying using the maven-gae-plugin gives the same results.
If I switch back to using 2.6.1 versions of gwt and the gwt-maven-plugin it deploys ok, so it would seem it's something to do with the automatic dev mode launcher.
Some of my pom.xml
<build>
<outputDirectory>${webappDirectory}/WEB-INF/classes</outputDirectory>
<resources>
<resource>
<directory>src/main/resources</directory>
</resource>
<resource>
<directory>src/main/super</directory>
</resource>
<resource>
<directory>${project.build.directory}/generated-sources/apt</directory>
</resource>
<resource>
<directory>${project.build.directory}/generated-sources/gwt</directory>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>${target.jdk}</source>
<target>${target.jdk}</target>
<encoding>${project.build.sourceEncoding}</encoding>
<proc>none</proc>
</configuration>
</plugin>
<!-- JUnit Testing - skip *.GwtTest cases -->
<!-- 'mvn test' - runs the Jukito tests -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>${maven-surefire-plugin.version}</version>
<configuration>
<includes>
<include>**/*Test.java</include>
</includes>
<excludes>
<exclude>**/*GwtTest.java</exclude>
<exclude>**/*JUnitTest.java</exclude>
</excludes>
</configuration>
</plugin>
<!-- GWT -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<version>${gwt-maven-plugin.version}</version>
<configuration>
<strict>true</strict>
<testTimeOut>180</testTimeOut>
<!-- With multiple tests use GwtTestSuite.java for speed -->
<includes>**/*GwtTest.java</includes>
<mode>htmlunit</mode>
<extraJvmArgs>-Xss1024k -Xmx2048M -XX:MaxPermSize=512M</extraJvmArgs>
<logLevel>INFO</logLevel>
<style>PRETTY</style>
<copyWebapp>true</copyWebapp>
<hostedWebapp>${webappDirectory}</hostedWebapp>
<server>com.google.appengine.tools.development.gwt.AppEngineLauncher</server>
<appEngineVersion>${gae.version}</appEngineVersion>
<appEngineHome>${gae.home}</appEngineHome>
<extraJvmArgs>-Dappengine.sdk.root=${gae.home}</extraJvmArgs>
<extraJvmArgs>-Ddatastore.default_high_rep_job_policy_unapplied_job_pct=20</extraJvmArgs>
<port>8888</port>
<runTarget>Project.html</runTarget>
<modules>
<module>com.utilitiessavings.usavappv7.Project</module>
</modules>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>test</goal>
</goals>
</execution>
</executions>
</plugin>
<!-- Google App Engine Deployment -->
<plugin>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>${gae.version}</version>
<configuration>
<enableJarSplitting>true</enableJarSplitting>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<!-- Google Web Toolkit dependencies -->
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-user</artifactId>
<version>${gwt.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-servlet</artifactId>
<version>${gwt.version}</version>
<scope>runtime</scope>
</dependency>
<!-- Google App Engine dependencies -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>${gae.version}</version>
</dependency>
<!-- Testing -->
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-labs</artifactId>
<version>${gae.version}</version>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-stubs</artifactId>
<version>${gae.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-testing</artifactId>
<version>${gae.version}</version>
<scope>test</scope>
</dependency>
<!-- Persistence dependencies -->
<dependency>
<groupId>javax.persistence</groupId>
<artifactId>persistence-api</artifactId>
<version>${persistence-api.version}</version>
</dependency>
<dependency>
<groupId>com.googlecode.objectify</groupId>
<artifactId>objectify</artifactId>
<version>${objectify.version}</version>
</dependency>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>${javax.validation.version}</version>
</dependency>
<!-- Other dependencies -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>${servlet-api.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
</dependencies>
In my Project.gwt.xml
<add-linker name="xsiframe" />
(Tried removing this line but still got the same result)
Environment
Eclipse Luna (4.4.1)
Maven 3.2.3 (3.2.1 Embedded)
m2eclipse 1.5.0
gwt:compile tries to work "incrementally" by comparing the timestamp of the nocache.js file with the ones of the source files, and skipping GWT compilation if it thinks the output is up-to-date. This is brittle though. gwt:run (without <superDevMode>false</superDevMode>; and gwt:run-codeserver with launcherDir) will overwrite the nocache.js with a SuperDevMode-specific version, and this is likely to lead to gwt:compile skipping the compilation.
The takeaway is: when deploying or "releasing", make sure you first run mvn clean or force gwt:compile to run by passing -Dgwt.compiler.force to Maven.
Just for information, I had the same problem, caused by the usage of a non-standard project structure.
Maven was copying the .nocache files in a directory different than /target/which prevented the clean plugin from cleaning the generated files.
Adding a new with the directory where the files are copied solves the problem.
来源：https://stackoverflow.com/questions/27186577/gwt-2-7-gae-app-looks-for-codeserver-when-deployed