Hi folks. Much to my surprise I found that one of my applications seemed to be running slow as a result of marshal.dumps. I think the culprit is the w_more(...) function, which grows the marshal buffer in 1k units. This means that a marshal of size 100k will have 100 reallocations and string copies. Other parts of Python (and java etc) have a proportional reallocation strategy which reallocates a new size based on the existing size. This mean a 100k marshal requires just 5 or so reallocations and string copies (n log n versus n**2 asymptotic performance). I humbly submit the following patch (based on python 2.6a0 source). I think it is a strict improvement on the existing code, but I've been wrong before (twice ;)). -- Aaron Watters PATCH FOLLOWS *** marshal.c.original 2008-01-10 10:15:40.686838800 -0500 --- marshal.c 2008-01-10 11:32:01.838654000 -0500 *************** *** 61,75 **** static void w_more(int c, WFILE *p) { Py_ssize_t size, newsize; if (p->str == NULL) return; /* An error already occurred */ size = PyString_Size(p->str); ! newsize = size + 1024; if (_PyString_Resize(&p->str, newsize) != 0) { p->ptr = p->end = NULL; } else { p->ptr = PyString_AS_STRING((PyStringObject *)p->str) + size; p->end = PyString_AS_STRING((PyStringObject *)p->str) + newsize; --- 61,76 ---- static void w_more(int c, WFILE *p) { Py_ssize_t size, newsize; if (p->str == NULL) return; /* An error already occurred */ size = PyString_Size(p->str); ! newsize = size + size + 1024; ! /* printf("new size %d\n", newsize); */ if (_PyString_Resize(&p->str, newsize) != 0) { p->ptr = p->end = NULL; } else { p->ptr = PyString_AS_STRING((PyStringObject *)p->str) + size; p->end = PyString_AS_STRING((PyStringObject *)p->str) + newsize;