I made dirty change in my local copy to allow branch filtering also for mercurial and discovery finally passed, repo started importing, issue solved :)

discover failed , and here's the last lines :

I checked source code(discoverMercurialCommits), it seems commitCache will only store in my case(repo never successfully imported) commits of tips of branches, so all duplicated commits from branches(ones that have common ancestor) that weren't merged and it seems also from inactive branches that are processed before branch that they were merged to will be stored in memory(I guess in refs[]). That might be my problem, with 300 branches and 90k commits I can easily get into millions. Also it seems shouldTrackBranch will return false only for git repos, removing this constraint might actually help me, in the end I'm only interested in one branch, will try it in my local copy of ph, is there any danger (data corruption, instability) in doing so ?

Thanks for quick response. There're slightly over 90k changesets in the repo (there are also couple of svn subrepos if that makes any difference). I ran discovery command you suggested, generally bunch of messages like this :