Algorithm 2 CKP_InitProcess( )

Ask_token (CHm); //ask for token if (token is assigned) then  WAIT (token); else  CSNi = CSNi+1; //increase its own CSN for (Pk ∈ PLm ∧ k ≠ i) do  SEND_DLrequest(Pk); //send DL request  CALCULATE(LDS, Pi);  DO_uncheckpoint(SCi);  UCi = 1; //change mark of uncertain CKP for (Pk ∈ LDS) do if (Pk ∈ DPm) then  SEND_CKPReq(CHm); //send CKP request else  SEND_CKPReq(Pk); if (Pi get all replies) then  CKP_Turning(SCi); //turn uncertain CKP to certain CKP for (Pk ∈ LDS) do if (Pk ∈ DPm) then  SEND_CKPturn(CHm); //send checkpoint turn request else  SEND_CKPturn (Pk);  FIND_CKPdeleted(IntraCDGfinal); //find the deletable checkpoints*/  NOTICE_CKPdeleted();  /*notice processes in same cluster of CKP elimination*/  MNi = 0; /*reset receiving messages number*/