private HRegion openHRegion(final CancelableProgressable reporter) throws IOException {
    try {
      CompoundConfiguration cConfig =
        new CompoundConfiguration().add(conf).addBytesMap(htableDescriptor.getValues());
      // Refuse to open the region if we are missing local compression support
      TableDescriptorChecker.checkCompression(cConfig, htableDescriptor);
      // Refuse to open the region if encryption configuration is incorrect or
      // codec support is missing
      LOG.debug("checking encryption for " + this.getRegionInfo().getEncodedName());
      TableDescriptorChecker.checkEncryption(cConfig, htableDescriptor);
      // Refuse to open the region if a required class cannot be loaded
      LOG.debug("checking classloading for " + this.getRegionInfo().getEncodedName());
      TableDescriptorChecker.checkClassLoading(cConfig, htableDescriptor);
      this.openSeqNum = initialize(reporter);
      this.mvcc.advanceTo(openSeqNum);
      // The openSeqNum must be increased every time when a region is assigned, as we rely on it to
      // determine whether a region has been successfully reopened. So here we always write open
      // marker, even if the table is read only.
      if (
        wal != null && getRegionServerServices() != null
          && RegionReplicaUtil.isDefaultReplica(getRegionInfo())
      ) {
        writeRegionOpenMarker(wal, openSeqNum);
      }
    } catch (Throwable t) {
      // By coprocessor path wrong region will open failed,
      // MetricsRegionWrapperImpl is already init and not close,
      // add region close when open failed
      try {
        // It is not required to write sequence id file when region open is failed.
        // Passing true to skip the sequence id file write.
        this.close(true);
      } catch (Throwable e) {
        LOG.warn("Open region: {} failed. Try close region but got exception ",
          this.getRegionInfo(), e);
      }
      throw t;
    }
    return this;
  }
Open HRegion.
<p/>
Calls initialize and sets sequenceId.
@return Returns <code>this</code>
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java