# [BUG] Out of memory on git log --simplify-by-decoration --first-parent 4 messages from 2012-06-08 to 2012-06-08. Participants: Vincent van Ravesteijn, Junio C Hamano. Thread: https://gitlist.dev/t/30748 ## Vincent van Ravesteijn, 2012-06-08 18:23 Subject: [BUG] Out of memory on git log --simplify-by-decoration --first-parent Message-ID: <4FD24330.2030805@lyx.org> URL: https://gitlist.dev/e/4FD24330.2030805%40lyx.org ``` git dies after calling the following command on the git repo: $ git log f623ca1c...b9cfa4e9 --simplify-by-decoration --first-parent This happens in simplify_merges () in revision.c. The list below shows the number of times the "while (list) { ..}" block is executed until git dies: 1475 3544 8274 19588 45689 106077 245329 565153 1269244 2614903 5871845 13138892 fatal: Out of memory, malloc failed (tried to allocate 8 bytes) Verified with msysgit and on Ubuntu Linux. Vincent ``` ## Junio C Hamano, 2012-06-08 20:09 Subject: Re: [BUG] Out of memory on git log --simplify-by-decoration --first-parent Message-ID: <7vwr3hbm6x.fsf@alter.siamese.dyndns.org> URL: https://gitlist.dev/e/7vwr3hbm6x.fsf%40alter.siamese.dyndns.org In-Reply-To: <4FD24330.2030805@lyx.org> ``` Vincent van Ravesteijn writes: > git dies after calling the following command on the git repo: > > $ git log f623ca1c...b9cfa4e9 --simplify-by-decoration --first-parent I wouldn't be surprised anything random happens when --first-parent is used together with simplify_merges(); the function needs full analysis of all commits in the specified range, and first-parent traversal specifically tells us not to descend into other parents. It might not be a bad idea to forbid this combination when the command line options are parsed. What information were you trying to get out of the above command? ``` ## Vincent van Ravesteijn, 2012-06-08 20:23 Subject: Re: [BUG] Out of memory on git log --simplify-by-decoration --first-parent Message-ID: <4FD25F34.1060400@lyx.org> URL: https://gitlist.dev/e/4FD25F34.1060400%40lyx.org In-Reply-To: <7vwr3hbm6x.fsf@alter.siamese.dyndns.org> ``` Op 8-6-2012 22:09, Junio C Hamano schreef: > Vincent van Ravesteijn writes: > >> git dies after calling the following command on the git repo: >> >> $ git log f623ca1c...b9cfa4e9 --simplify-by-decoration --first-parent > I wouldn't be surprised anything random happens when --first-parent > is used together with simplify_merges(); the function needs full > analysis of all commits in the specified range, and first-parent > traversal specifically tells us not to descend into other parents. > It might not be a bad idea to forbid this combination when the > command line options are parsed. > > What information were you trying to get out of the above command? I was using gitk and I tried to simplify the history a bit, just for visualization,... so I tried by checking "Limit to first parent" and "Simple history". Then, git errored out with an out-of-memory error. Vincent ``` ## Junio C Hamano, 2012-06-08 22:01 Subject: Re: [BUG] Out of memory on git log --simplify-by-decoration --first-parent Message-ID: <7vr4tpbgz0.fsf@alter.siamese.dyndns.org> URL: https://gitlist.dev/e/7vr4tpbgz0.fsf%40alter.siamese.dyndns.org In-Reply-To: <4FD25F34.1060400@lyx.org> ``` Vincent van Ravesteijn writes: > Op 8-6-2012 22:09, Junio C Hamano schreef: >> Vincent van Ravesteijn writes: >> >>> git dies after calling the following command on the git repo: >>> >>> $ git log f623ca1c...b9cfa4e9 --simplify-by-decoration --first-parent > ... >> What information were you trying to get out of the above command? > > I was using gitk and I tried to simplify the history a bit, just for > visualization,... so I tried by checking "Limit to first parent" and > "Simple history". Then, git errored out with an out-of-memory error. I see. I am not sure what it _means_ to simplify merges away in a history that is showing first-parent-only ancestry, but in any case, this patch may help. -- >8 -- Subject: [PATCH] revision: cull side parents before running simplify-merges The simplify_merges() function needs to look at all history chain to find the closest ancestor that is relevant after the simplification, but after --first-parent traversal, side parents haven't been marked for relevance (they are irrelevant by definition due to the nature of first-parent-only traversal) nor culled from the parents list of resulting commits. Remove these side parents from parents list before starting to further simplifying the result. --- revision.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) diff --git a/revision.c b/revision.c index 935e7a7..acfdbac 100644 --- a/revision.c +++ b/revision.c @@ -1358,11 +1358,13 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg revs->topo_order = 1; } else if (!strcmp(arg, "--simplify-merges")) { revs->simplify_merges = 1; + revs->topo_order = 1; revs->rewrite_parents = 1; revs->simplify_history = 0; revs->limited = 1; } else if (!strcmp(arg, "--simplify-by-decoration")) { revs->simplify_merges = 1; + revs->topo_order = 1; revs->rewrite_parents = 1; revs->simplify_history = 0; revs->simplify_by_decoration = 1; @@ -2013,25 +2015,31 @@ static struct commit_list **simplify_one(struct rev_info *revs, struct commit *c static void simplify_merges(struct rev_info *revs) { - struct commit_list *list; + struct commit_list *list, *next; struct commit_list *yet_to_do, **tail; + struct commit *commit; - if (!revs->topo_order) - sort_in_topological_order(&revs->commits, revs->lifo); if (!revs->prune) return; /* feed the list reversed */ yet_to_do = NULL; - for (list = revs->commits; list; list = list->next) - commit_list_insert(list->item, &yet_to_do); + for (list = revs->commits; list; list = next) { + commit = list->item; + next = list->next; + free(list); + if (revs->first_parent_only && + commit->parents && commit->parents->next) + commit->parents->next = NULL; + commit_list_insert(commit, &yet_to_do); + } while (yet_to_do) { list = yet_to_do; yet_to_do = NULL; tail = &yet_to_do; while (list) { - struct commit *commit = list->item; - struct commit_list *next = list->next; + commit = list->item; + next = list->next; free(list); list = next; tail = simplify_one(revs, commit, tail); @@ -2043,9 +2051,10 @@ static void simplify_merges(struct rev_info *revs) revs->commits = NULL; tail = &revs->commits; while (list) { - struct commit *commit = list->item; - struct commit_list *next = list->next; struct merge_simplify_state *st; + + commit = list->item; + next = list->next; free(list); list = next; st = locate_simplify_state(revs, commit); ```