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From "Tadimeti, Veera" <veera.tadim...@epsilon.com>
Subject scope of RegionCoprocessorEnvironment sharedData
Date Thu, 06 Jul 2017 14:14:04 GMT

I have few questions regarding scope of RegionCoprocessorEnvironment sharedData.

*  Is sharedData map is shared accross all instances simultaneously ?
o  I am putting a variable in sharedData in preScannerOpen() based on scan attribute,
o check that variable exists in postScannerNext() then apply logic,
o remove the variable postScannerClose().
o If data is in multiple regions, when one coprocessor removes variable in postScannerClose(),
will the variable is NULL for another region coprocessor in postScannerNext() ?
*      Is sharedData map is shared across all the client request operations ?
If a variable is set in sharedData for one client operation(say SCAN), will the variable is
available for another client operation(new SCAN) ?

*   Will the variables be garbage collected even if we dont implement (removed variables in
sharedData) postScannerClose() method

Please find below the logic that I am using currently

    public RegionScanner preScannerOpen(ObserverContext<RegionCoprocessorEnvironment>
e, Scan scan, RegionScanner s) throws IOException {
        byte[] useGetInPostScannerNext = scan.getAttribute(USE_GET_OPERATION_IN_POST_SCANNER_NEXT);
        String useGetInPostScannerNextStr = Bytes.toString(useGetInPostScannerNext);
        if (Boolean.parseBoolean(useGetInPostScannerNextStr)) {
        return super.preScannerOpen(e, scan, s);

    public boolean postScannerNext(final ObserverContext<RegionCoprocessorEnvironment>
            final InternalScanner s, final List<Result> results, final int limit,
            final boolean hasMore) throws IOException {
        try {

            if (canUseGetOperation(e)) {

               //logic goes here
        } catch (Exception ex) {
            logger.error("Exception in postScannerNext ", ex);
            throw new IOException(ex);
        return hasMore;

    public void postScannerClose(ObserverContext<RegionCoprocessorEnvironment> e, InternalScanner
s) throws IOException {
        if (canUseGetOperation(e)) {
        super.postScannerClose(e, s);

    private boolean canUseGetOperation(final ObserverContext<RegionCoprocessorEnvironment>
e) {
        String useGetOperationInPostScannerNext = (String) e.getEnvironment().getSharedData().get(USE_GET_OPERATION_IN_POST_SCANNER_NEXT);
        return Boolean.parseBoolean(useGetOperationInPostScannerNext);

Thanks & Regards,
Veera Tadimeti

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