[HBASE-14873] Problems around BoundedByteBufferPool providing direct buffers

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Assignee: Hiroshi Ikeda
• Reporter: Hiroshi Ikeda
• Created: 24/Nov/15 08:44
• Updated: 04/Dec/15 18:24

Description

HBASE-13819 made BoundedByteBufferPool provide direct buffers.

See RpcServer.java:

...
class Call implements RpcCallContext {
  protected synchronized void setResponse(...) {
...
    this.cellBlock = ipcUtil.buildCellBlock(..., reservoir);
...
    bc = new BufferChain(..., this.cellBlock);
    if (connection.useWrap) {
      bc = wrapWithSasl(bc);
    }
...
  private BufferChain wrapWithSasl(BufferChain bc) throws IOException {
...
    byte[] responseBytes = bc.getBytes();
...

cellBlock is expected to be a direct buffer retrieved from reservoir (but not always), and bc may be composed of both direct and non-direct buffers.

And then, see BufferChain.java:

byte [] getBytes() {
...
    for (ByteBuffer bb: this.buffers) {
      System.arraycopy(bb.array(), ...);

A direct buffer doesn't give its array, and will throw UnsupportedOperationException.

Another problem; cellBlock is allowed to be a non-direct buffer, and after use it will be put to reservoir, mixing direct and non-direct buffers in the pool.