Can I put the renderscript memory allocation inside a loop to process a series of variable size arrays? - algorithm

Question

I am trying to modify the parallel reduction algorithm. I am using a logic to divide an given array length into powers of 2. For example if i put in the number 26, I make array 1 of 16 elements, the next array of 8 elements and the last array of 2 elements. Although 26 in itself is not a power of 2 but by this method i have more number of sub arrays created from the main array where each of them can be subjected to parallel reduction. but to be able to do this in rendercript i use a loop to each time rewrite the renderscript memory allocation while it has only one context but it is throwing me errors. can you help me in this part? point me to my blind spot? the following is my code!
private void createScript() {
log ("i'm in createscript");
int pp=0;
int qq=1;
int ii=0;
**mRS = RenderScript.create(this);**
for (int gstride=0; gstride < address.length/2; gstride++){
log("im in stride noof gstride:"+gstride);
// this is the address array location
int strtadd=address[ii];
int sze = 0;
sze=address[qq]-address[pp]+1;
tempin =new int [sze];
System.arraycopy(input, strtadd, tempin, 0, tempin.length);
strtadd=address[ii+2];
log("Generated size of array: " + tempin.length);
//renderscript declarations
`enter code here`**mInAllocation=Allocation.createSized(mRS,Element.I32(mRS),tempin.length);
`enter code here`mOutAllocation=Allocation.createSized(mRS,Element.I32(mRS),address.length/2); `
mInAllocation.copyFrom(tempin);
mScript = new ScriptC_reduce2(mRS, getResources(), R.raw.reduce2);
//int row_width = input.length;
mScript.bind_gInarray(mInAllocation);
mScript.set_gIn(mInAllocation);
mScript.set_gOut(mOutAllocation);
mScript.set_gScript(mScript);
//time measurement
long lStartTime = new Date().getTime();
for (int stride = tempin.length / 2; stride > 0; stride /= 2) {
mScript.set_stride(stride);
mScript.invoke_filter();
}**
long lEndTime = new Date().getTime();
long difference = lEndTime - lStartTime;
nettime[gstride]=difference;
pp=pp+1;
qq=qq+1;
mInAllocation.copyTo(tempin);
output[gstride] = tempin[0];
}
int sum=0;
int sum2=0;
int i = 0; .
while(i < output.length) {
sum += output[i];
sum2 +=nettime[i];
i++;
}
t1.setText(String.format("output:%s\n\nExecution time:%s",
+sum, +sum2 +"ms")); //input:%s\n\n ArrayToString(input),
}
I get the following error as copied from the error log: I don't think its out of memory ` `error.
V/RenderScript( 2890): rsContextCreate dev=0x2a14ea68
V/ScriptC ( 2890): Create script for resource = reduce2
D/StopWatch( 2890): StopWatch bcc: RSCompilerDriver::loadScriptCache time (us): 1988
D/StopWatch( 2890): StopWatch bcc: RSCompilerDriver::build time (us): 2485
D/AndroidRuntime( 2890): Shutting down VM
W/dalvikvm( 2890): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
E/AndroidRuntime( 2890): FATAL EXCEPTION: main
E/AndroidRuntime( 2890): java.lang.RuntimeException: Unable to start activity `enter code `enter code here`ComponentInfo{com.example.paralleladd2/com.example.paralleladd2.Paralleladd2}:java.lang .NullPointerException
E/AndroidRuntime( 2890): at `enter code here`android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
E/AndroidRuntime( 2890): at `enter code here`android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
E/AndroidRuntime( 2890): at android.app.ActivityThread.access$600(ActivityThread.java:141)
E/AndroidRuntime( 2890): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
E/AndroidRuntime( 2890): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime( 2890): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime( 2890): at android.app.ActivityThread.main(ActivityThread.java:5041)
E/AndroidRuntime( 2890): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 2890): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime( 2890): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
E/AndroidRuntime( 2890): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
E/AndroidRuntime( 2890): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime( 2890): Caused by: java.lang.NullPointerException
E/AndroidRuntime( 2890): at com.example.paralleladd2.Paralleladd2.createScript(Paralleladd2.java:157)
E/AndroidRuntime( 2890): at com.example.paralleladd2.Paralleladd2.onCreate(Paralleladd2.java:48)
E/AndroidRuntime( 2890): at android.app.Activity.performCreate(Activity.java:5104)
E/AndroidRuntime( 2890): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
E/AndroidRuntime( 2890): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)

Answer 1

Allocation creation should be fine inside the loop. I think your problem is coming from having the script creation inside the loop. I would create one reduce script outside your allocation creation loop and re-use it in the loop.
Script creation is very resource intensive and could be running the system out of resources.