A simpler version of the distributed garbage collection algorithm just invokes addRef at the site where a remote object lives whenever a proxy is created and removeRef whenever a proxy is deleted. Outline all the possible effects of communication and process failures on the algorithm. Suggest how to overcome each of these effects, but without using leases.

What will be an ideal response?


AddRef message lost - the owning site doesn’t know about the client’s proxy and may delete the remote object when it is still needed. (The client does not allow for this failure).
RemoveRef message lost - the owning site doesn’t know the remote object has one less user. It may continue to keep the remote object when it is no longer needed.
Process holding a proxy crashes - owning site may continue to keep the remote object when it is no longer needed.

Site owning a remote object crashes. Will not affects garbage collection algorithm

When a removeRef fails, the client can repeat the call until either it succeeds or the owner’s failure has been detected.
One solution to a proxy holder crashing is for the owning sites to set failure detectors on holding sites and then remove holders after they are known to have failed.

Computer Science & Information Technology

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