When a thread requests an available resource, system must decide

if immediate allocation leaves the system in a safe state

System is in safe state if there exists a sequence

of ALL the threads in the systems such that for each $T_i,$ the

resources that $T_i$ can still request can be satisfied by currently

available resources $+$ resources held by all the $T_j,$ with $T_i{T}_i{T}_j{T}_j{T}_i{T}_i{T}_{i+1}j$

That $is$:

$If{T}_i$ resource needs are not immediately available, then $T_i$ can

wait until all $T_j$ have finished

When $T_{j}is$ finished, $T_i$ can obtain needed resources, execute,

return allocated resources, and terminate

When $T_i$ terminates, $T_{i+1}$ can obtain its needed resources, and

$soon$