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Yes, I do not know what this paragraph wants to say: > "The first memory allocation scheme started with a stack-based memory allocation. Next came the dynamic-
by adrian_b 14d ago
Yes, I do not know what this paragraph wants to say:
> "The first memory allocation scheme started with a stack-based memory allocation. Next came the dynamic-based memory allocation scheme where linked-list and bucket-heap mechanism are used to divide the private-heap using size class approach. Soon, garbage collection algorithm introduced the initial backend of the memory allocation scheme."
Since no specific operating system is mentioned, these sentences appear to refer to the general history of dynamic memory allocation, in which case they are wrong.
"malloc" is a late comer in this history. It has appeared as the statement "ALLOCATE", together with the statement "FREE", in the programming language PL/I of IBM, by the end of 1964. The C programming language has inherited these 2 functions from IBM PL/I, together with several other features.
At that time (1964-12), many other techniques of managing memory had already been used for a few years.
Dynamic allocation of memory has started during the fifties, with allocation without ever freeing the allocated memory before the termination of the process.
Then, in 1960, 3 methods of handling dynamic memory allocation and implicit freeing were published, which have remained important until today: the use of garbage collectors in April (John McCarthy), the use of stacks in May (E. W. Dijkstra), and the use of reference counts in December (George E. Collins @ IBM).
So the use of garbage collectors is actually the oldest published method for handling dynamic memory allocation, not a newer method, being used in LISP I about 5 years before the first release of PL/I with explicit allocation and freeing (mid 1965).
- egberts1 14d agoThank you for the insightful aspect. This too should be in the lore of memory allocations as well Will research that, citations and all
- adrian_b 14d agoTo help you with the citations: Garbage collectors: "Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I", John McCarthy, Communications of the ACM, 1960-04, pp. 184-195 (open access at ACM). Stacks and stack pointers: "Recursive Programming", Edsger Wybe Dijkstra, 1960-05-11 (available at the Dijkstra Archive). Reference counts for memory allocation: "A Method for Overlapping and Erasure of Lists", George E. Collins (IBM), Communications of the ACM, Volume 3, Issue 12, 1960-12, pp. 655–657 (open access at ACM). The first "malloc", i.e. the statements "ALLOCATE" and "FREE" appeared in "NPL Technical Report" at IBM in 1964-12 (available at bitsavers.org). "NPL" was a provisional name for the new programming language of IBM, which was rebranded as "PL/I" when it was launched officially, a half of year later. IBM did not document what kind of algorithm was used by their "malloc" implementation, but it already had to handle multi-threaded programs and it was specified that when a new thread was spawned, it could still access any variable that had been dynamically allocated in the parent thread, before the launching of the new thread, but the variables that were allocated in the new thread were private to that thread. The C "malloc" became compatible with multi-threading only many decades after its ancestor from PL/I.
- egberts1 14d agoZeow! Citation galore! Gotta RAG them into my LLM! And then THeIR citations too! Thank you very much!