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Created October 16, 2015 at 8:27 PM
Updated January 11, 2016 at 2:40 PM
Resolved January 11, 2016 at 2:40 PM
Android Lollipop (API level 21) introduced an advanced bytecode checker that does not allow Clojure 1.8 to run.
Here is an example repo that reproduces the issue:
https://github.com/konmik/try_clojure_on_android/blob/master/app/src/main/java/com/clojure_on_android/TestInvokeUnit.java#L8
It uses 'org.clojure:clojure:1.8.0-beta1' dependency.
To reproduce the exception you need to install Android Studio
https://developer.android.com/sdk/index.html
and an android emulator https://www.genymotion.com/
Run the emulator, open the project and press "run" in the IDE.
The expected result that I get on Android API < 21 is:
https://github.com/konmik/try_clojure_on_android/blob/master/expected.png
On Android versions >= 21 I get:
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: java.lang.VerifyError: Rejecting class clojure.core.server$stop_server because it failed compile-time verification (declaration of 'clojure.core.server$stop_server' appears in /data/app/com.clojure_on_android-1/base.apk)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core.server__init.load(Unknown Source)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core.server__init.<clinit>(Unknown Source)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at java.lang.Class.classForName(Native Method)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at java.lang.Class.forName(Class.java:309)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RT.classForName(RT.java:2168)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RT.classForName(RT.java:2177)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RT.loadClassForName(RT.java:2196)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RT.load(RT.java:443)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RT.load(RT.java:419)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load$fn__5669.invoke(core.clj:5885)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load.invokeStatic(core.clj:5884)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load_one.invokeStatic(core.clj:5685)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load_one.invoke(core.clj)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load_lib$fn__5618.invoke(core.clj:5730)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load_lib.invokeStatic(core.clj:5729)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load_lib.doInvoke(core.clj)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RestFn.applyTo(RestFn.java:142)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$apply.invokeStatic(core.clj:647)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load_libs.invokeStatic(core.clj:5767)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$load_libs.doInvoke(core.clj)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RestFn.applyTo(RestFn.java:137)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$apply.invokeStatic(core.clj:647)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$require.invokeStatic(core.clj:5789)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.core$require.doInvoke(core.clj)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RestFn.invoke(RestFn.java:408)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.Var.invoke(Var.java:379)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RT.doInit(RT.java:480)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.RT.<clinit>(RT.java:331)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.Namespace.<init>(Namespace.java:34)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.Namespace.findOrCreate(Namespace.java:176)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.lang.Var.intern(Var.java:146)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.java.api.Clojure.var(Clojure.java:82)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at clojure.java.api.Clojure.<clinit>(Clojure.java:96)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at com.clojure_on_android.TestInvokeUnit.invokePlus(TestInvokeUnit.java:8)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at com.clojure_on_android.MainActivity.onCreate(MainActivity.java:15)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.app.Activity.performCreate(Activity.java:5990)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.app.ActivityThread.access$800(ActivityThread.java:151)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:102)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.os.Looper.loop(Looper.java:135)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5254)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:372)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
10-16 14:49:26.801 2008-2008/? E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Cause: In Clojure 1.8, the socket server code is loaded during startup, which causes classes to be loaded that are compiled with the locking macro. The locking macro generates monitorenter and monitorexit instructions (and exception handlers) that do not conform to the (optional) structured locking section of the JVM spec. While this code is considered valid in OracleJDK, OpenJDK, etc the new Android bytecode checker will fail with it. Other versions of Clojure also have this verification issue, but the use of the locking macro during language boot time changes this potential issue to always being a problem.
Approach: The proposed patch sidesteps this issue by avoiding the locking macro and replaces it with a similar macro that uses ReentrantLock instead. This approach has been verified on the provided test case.
Patch: clj-1829.patch
Alternatives: There is a patch available for the locking macro (https://clojure.atlassian.net/browse/CLJ-1472#icft=CLJ-1472) that replaces the locking macro by a synchronized block instead.