Can't access a local mongodb database. Keeps getting access denied ("java.lang.RuntimePermission" "modifyThreadGroup")

[Abhishek Vaid]

- I'm building a simple Servlet Application on Google App Engine.
- I have a Servlet and I'm able to successfully reach its doGet method.
- However, when I try to establish a MongoClient on my localhost, I get the exception:

access denied ("java.lang.RuntimePermission" "modifyThreadGroup")

- The Error is triggered by following line:

client = new MongoClient(hostName);

- Can someone explain to me what am I doing wrong?

java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
    at java.security.AccessControlContext.checkPermission(AccessControlContext.java:457)
    at java.security.AccessController.checkPermission(AccessController.java:884)
    at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
    at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkPermission(DevAppServerFactory.java:429)
    at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkAccess(DevAppServerFactory.java:454)
    at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
    at java.lang.Thread.init(Thread.java:391)
    at java.lang.Thread.init(Thread.java:349)
    at java.lang.Thread.<init>(Thread.java:548)
    at com.mongodb.ServerMonitor.<init>(ServerMonitor.java:66)
    at com.mongodb.DefaultServer.<init>(DefaultServer.java:45)
    at com.mongodb.DefaultClusterableServerFactory.create(DefaultClusterableServerFactory.java:44)
    at com.mongodb.BaseCluster.createServer(BaseCluster.java:235)
    at com.mongodb.SingleServerCluster.<init>(SingleServerCluster.java:45)
    at com.mongodb.Clusters.create(Clusters.java:32)
    at com.mongodb.DBTCPConnector.start(DBTCPConnector.java:72)
    at com.mongodb.Mongo.<init>(Mongo.java:346)
    at com.mongodb.MongoClient.<init>(MongoClient.java:167)
    at com.mongodb.MongoClient.<init>(MongoClient.java:152)
    at com.mongodb.MongoClient.<init>(MongoClient.java:127)
    at com.mongodb.MongoClient.<init>(MongoClient.java:92)

[Marcial Roman]

App Engine "sandbox" environment imposes some restrictions on what can be done. As it is stated in public documentation [1]:

"... you must use one of the methods on ThreadManager to create your threads. You cannot invoke new Thread() yourself or use the default thread factory."

...and that is what ServerMonitor.java is trying to do [2].

It looks like if a a workaround exists, it will not be trivial [3].

[1] https://cloud.google.com/appengine/docs/java/#Java_The_sandbox
[2] http://grepcode.com/file/repo1.maven.org/maven2/org.mongodb/mongo-java-driver/2.12.3/com/mongodb/ServerMonitor.java#66

[3] http://stackoverflow.com/questions/25216069/google-app-engine-and-mongodb