{"action":"created","comment":{"url":"https://api.github.com/repos/apple/swift/pulls/comments/182275558","pull_request_review_id":113039966,"id":182275558,"diff_hunk":"@@ -107,9 +107,11 @@ public:\n   /// \\returns true on error, false on success\n   bool execute();\n \n-  /// \\brief Reads data from the pipes, if any is available.\n-  /// \\returns true on error, false on success\n-  bool readFromPipes();\n+  /// \\brief Reads data from the pipes, if any is available. If\n+  /// \\p untilEnd is true, reads until the end of the stream; otherwise\n+  /// reads once (posslby with a retry on EINTR), and returns.\n+  /// \\returns true on error, false on success.\n+  bool readFromPipes(bool untilEnd=true);","path":"lib/Basic/Unix/TaskQueue.inc","position":11,"original_position":11,"commit_id":"29107fc30c24655abaebedc065fbb64616e75a06","original_commit_id":"29107fc30c24655abaebedc065fbb64616e75a06","user":{"login":"jrose-apple","id":15097531,"avatar_url":"https://avatars2.githubusercontent.com/u/15097531?v=4","gravatar_id":"","url":"https://api.github.com/users/jrose-apple","html_url":"https://github.com/jrose-apple","followers_url":"https://api.github.com/users/jrose-apple/followers","following_url":"https://api.github.com/users/jrose-apple/following{/other_user}","gists_url":"https://api.github.com/users/jrose-apple/gists{/gist_id}","starred_url":"https://api.github.com/users/jrose-apple/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jrose-apple/subscriptions","organizations_url":"https://api.github.com/users/jrose-apple/orgs","repos_url":"https://api.github.com/users/jrose-apple/repos","events_url":"https://api.github.com/users/jrose-apple/events{/privacy}","received_events_url":"https://api.github.com/users/jrose-apple/received_events","type":"User","site_admin":false},"body":"I think convention definitely skews towards including the spaces.","created_at":"2018-04-17T23:58:12Z","updated_at":"2018-04-18T00:02:31Z","html_url":"https://github.com/apple/swift/pull/15999#discussion_r182275558","pull_request_url":"https://api.github.com/repos/apple/swift/pulls/15999","author_association":"OWNER","_links":{"self":{"href":"https://api.github.com/repos/apple/swift/pulls/comments/182275558"},"html":{"href":"https://github.com/apple/swift/pull/15999#discussion_r182275558"},"pull_request":{"href":"https://api.github.com/repos/apple/swift/pulls/15999"}},"in_reply_to_id":182266684},"pull_request":{"url":"https://api.github.com/repos/apple/swift/pulls/15999","id":182326319,"html_url":"https://github.com/apple/swift/pull/15999","diff_url":"https://github.com/apple/swift/pull/15999.diff","patch_url":"https://github.com/apple/swift/pull/15999.patch","issue_url":"https://api.github.com/repos/apple/swift/issues/15999","number":15999,"state":"open","locked":false,"title":"[Driver] <rdar://39504759> Continue demultiplexing subprocess output after initial read.","user":{"login":"graydon","id":14097,"avatar_url":"https://avatars3.githubusercontent.com/u/14097?v=4","gravatar_id":"","url":"https://api.github.com/users/graydon","html_url":"https://github.com/graydon","followers_url":"https://api.github.com/users/graydon/followers","following_url":"https://api.github.com/users/graydon/following{/other_user}","gists_url":"https://api.github.com/users/graydon/gists{/gist_id}","starred_url":"https://api.github.com/users/graydon/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/graydon/subscriptions","organizations_url":"https://api.github.com/users/graydon/orgs","repos_url":"https://api.github.com/users/graydon/repos","events_url":"https://api.github.com/users/graydon/events{/privacy}","received_events_url":"https://api.github.com/users/graydon/received_events","type":"User","site_admin":false},"body":"This is a followup to rdar://39332957 in which it was observed that a batch mode run with -Xfrontend -debug-time-function-bodies seemed to be slowing down quite a bit.\r\n\r\nTurns out that the driver's task queue polling loop, while it _does_ poll for readiness on each of its child fds, then assumes that initial readiness on an fd means _all_ data the child is going to write is now available, so does blocking reads on the pipe until it ends as soon as the first byte is available.\r\n\r\nThis is Very Wrong. It means that if multiple subprocesses trickle output, the poll loop switches to serializing them, draining the entirety of the first subprocess' pipe while the others are blocked on full pipes, then moving on to the second, and so forth.\r\n\r\nThis happens independently of batch mode, and is unrelated to the error-stream separation (turns out we only separate error streams when running xcrun anyways).\r\n\r\nLong term the polling loop here has become quite a mess and needs substantial refactoring / rewriting. Short term, this can be hacked-around by passing a flag to the two non-terminal read loops to cause them to exit after the first successful read they execute (thus returning to the poll loop and continuing to interleave reads from other children).","created_at":"2018-04-17T22:56:24Z","updated_at":"2018-04-18T00:02:32Z","closed_at":null,"merged_at":null,"merge_commit_sha":"d1d994080a26b93c1700bfb343a97aa126f744ab","assignee":null,"assignees":[],"requested_reviewers":[],"requested_teams":[],"labels":[],"milestone":null,"commits_url":"https://api.github.com/repos/apple/swift/pulls/15999/commits","review_comments_url":"https://api.github.com/repos/apple/swift/pulls/15999/comments","review_comment_url":"https://api.github.com/repos/apple/swift/pulls/comments{/number}","comments_url":"https://api.github.com/repos/apple/swift/issues/15999/comments","statuses_url":"https://api.github.com/repos/apple/swift/statuses/29107fc30c24655abaebedc065fbb64616e75a06","head":{"label":"graydon:rdar-39504759-keep-demultiplexing-after-first-read","ref":"rdar-39504759-keep-demultiplexing-after-first-read","sha":"29107fc30c24655abaebedc065fbb64616e75a06","user":{"login":"graydon","id":14097,"avatar_url":"https://avatars3.githubusercontent.com/u/14097?v=4","gravatar_id":"","url":"https://api.github.com/users/graydon","html_url":"https://github.com/graydon","followers_url":"https://api.github.com/users/graydon/followers","following_url":"https://api.github.com/users/graydon/following{/other_user}","gists_url":"https://api.github.com/users/graydon/gists{/gist_id}","starred_url":"https://api.github.com/users/graydon/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/graydon/subscriptions","organizations_url":"https://api.github.com/users/graydon/orgs","repos_url":"https://api.github.com/users/graydon/repos","events_url":"https://api.github.com/users/graydon/events{/privacy}","received_events_url":"https://api.github.com/users/graydon/received_events","type":"User","site_admin":false},"repo":{"id":66865548,"name":"swift","full_name":"graydon/swift","owner":{"login":"graydon","id":14097,"avatar_url":"https://avatars3.githubusercontent.com/u/14097?v=4","gravatar_id":"","url":"https://api.github.com/users/graydon","html_url":"https://github.com/graydon","followers_url":"https://api.github.com/users/graydon/followers","following_url":"https://api.github.com/users/graydon/following{/other_user}","gists_url":"https://api.github.com/users/graydon/gists{/gist_id}","starred_url":"https://api.github.com/users/graydon/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/graydon/subscriptions","organizations_url":"https://api.github.com/users/graydon/orgs","repos_url":"https://api.github.com/users/graydon/repos","events_url":"https://api.github.com/users/graydon/events{/privacy}","received_events_url":"https://api.github.com/users/graydon/received_events","type":"User","site_admin":false},"private":false,"html_url":"https://github.com/graydon/swift","description":"The Swift Programming Language","fork":true,"url":"https://api.github.com/repos/graydon/swift","forks_url":"https://api.github.com/repos/graydon/swift/forks","keys_url":"https://api.github.com/repos/graydon/swift/keys{/key_id}","collaborators_url":"https://api.github.com/repos/graydon/swift/collaborators{/collaborator}","teams_url":"https://api.github.com/repos/graydon/swift/teams","hooks_url":"https://api.github.com/repos/graydon/swift/hooks","issue_events_url":"https://api.github.com/repos/graydon/swift/issues/events{/number}","events_url":"https://api.github.com/repos/graydon/swift/events","assignees_url":"https://api.github.com/repos/graydon/swift/assignees{/user}","branches_url":"https://api.github.com/repos/graydon/swift/branches{/branch}","tags_url":"https://api.github.com/repos/graydon/swift/tags","blobs_url":"https://api.github.com/repos/graydon/swift/git/blobs{/sha}","git_tags_url":"https://api.github.com/repos/graydon/swift/git/tags{/sha}","git_refs_url":"https://api.github.com/repos/graydon/swift/git/refs{/sha}","trees_url":"https://api.github.com/repos/graydon/swift/git/trees{/sha}","statuses_url":"https://api.github.com/repos/graydon/swift/statuses/{sha}","languages_url":"https://api.github.com/repos/graydon/swift/languages","stargazers_url":"https://api.github.com/repos/graydon/swift/stargazers","contributors_url":"https://api.github.com/repos/graydon/swift/contributors","subscribers_url":"https://api.github.com/repos/graydon/swift/subscribers","subscription_url":"https://api.github.com/repos/graydon/swift/subscription","commits_url":"https://api.github.com/repos/graydon/swift/commits{/sha}","git_commits_url":"https://api.github.com/repos/graydon/swift/git/commits{/sha}","comments_url":"https://api.github.com/repos/graydon/swift/comments{/number}","issue_comment_url":"https://api.github.com/repos/graydon/swift/issues/comments{/number}","contents_url":"https://api.github.com/repos/graydon/swift/contents/{+path}","compare_url":"https://api.github.com/repos/graydon/swift/compare/{base}...{head}","merges_url":"https://api.github.com/repos/graydon/swift/merges","archive_url":"https://api.github.com/repos/graydon/swift/{archive_format}{/ref}","downloads_url":"https://api.github.com/repos/graydon/swift/downloads","issues_url":"https://api.github.com/repos/graydon/swift/issues{/number}","pulls_url":"https://api.github.com/repos/graydon/swift/pulls{/number}","milestones_url":"https://api.github.com/repos/graydon/swift/milestones{/number}","notifications_url":"https://api.github.com/repos/graydon/swift/notifications{?since,all,participating}","labels_url":"https://api.github.com/repos/graydon/swift/labels{/name}","releases_url":"https://api.github.com/repos/graydon/swift/releases{/id}","deployments_url":"https://api.github.com/repos/graydon/swift/deployments","created_at":"2016-08-29T17:37:10Z","updated_at":"2018-04-10T23:44:15Z","pushed_at":"2018-04-17T22:03:20Z","git_url":"git://github.com/graydon/swift.git","ssh_url":"git@github.com:graydon/swift.git","clone_url":"https://github.com/graydon/swift.git","svn_url":"https://github.com/graydon/swift","homepage":"https://swift.org/","size":273324,"stargazers_count":5,"watchers_count":5,"language":"C++","has_issues":false,"has_projects":true,"has_downloads":true,"has_wiki":false,"has_pages":false,"forks_count":0,"mirror_url":null,"archived":false,"open_issues_count":0,"license":{"key":"apache-2.0","name":"Apache License 2.0","spdx_id":"Apache-2.0","url":"https://api.github.com/licenses/apache-2.0"},"forks":0,"open_issues":0,"watchers":5,"default_branch":"master"}},"base":{"label":"apple:master","ref":"master","sha":"c4121c7cc4c065c8f7a9af8aa5e4be399ac80811","user":{"login":"apple","id":10639145,"avatar_url":"https://avatars0.githubusercontent.com/u/10639145?v=4","gravatar_id":"","url":"https://api.github.com/users/apple","html_url":"https://github.com/apple","followers_url":"https://api.github.com/users/apple/followers","following_url":"https://api.github.com/users/apple/following{/other_user}","gists_url":"https://api.github.com/users/apple/gists{/gist_id}","starred_url":"https://api.github.com/users/apple/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/apple/subscriptions","organizations_url":"https://api.github.com/users/apple/orgs","repos_url":"https://api.github.com/users/apple/repos","events_url":"https://api.github.com/users/apple/events{/privacy}","received_events_url":"https://api.github.com/users/apple/received_events","type":"Organization","site_admin":false},"repo":{"id":44838949,"name":"swift","full_name":"apple/swift","owner":{"login":"apple","id":10639145,"avatar_url":"https://avatars0.githubusercontent.com/u/10639145?v=4","gravatar_id":"","url":"https://api.github.com/users/apple","html_url":"https://github.com/apple","followers_url":"https://api.github.com/users/apple/followers","following_url":"https://api.github.com/users/apple/following{/other_user}","gists_url":"https://api.github.com/users/apple/gists{/gist_id}","starred_url":"https://api.github.com/users/apple/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/apple/subscriptions","organizations_url":"https://api.github.com/users/apple/orgs","repos_url":"https://api.github.com/users/apple/repos","events_url":"https://api.github.com/users/apple/events{/privacy}","received_events_url":"https://api.github.com/users/apple/received_events","type":"Organization","site_admin":false},"private":false,"html_url":"https://github.com/apple/swift","description":"The Swift Programming Language","fork":false,"url":"https://api.github.com/repos/apple/swift","forks_url":"https://api.github.com/repos/apple/swift/forks","keys_url":"https://api.github.com/repos/apple/swift/keys{/key_id}","collaborators_url":"https://api.github.com/repos/apple/swift/collaborators{/collaborator}","teams_url":"https://api.github.com/repos/apple/swift/teams","hooks_url":"https://api.github.com/repos/apple/swift/hooks","issue_events_url":"https://api.github.com/repos/apple/swift/issues/events{/number}","events_url":"https://api.github.com/repos/apple/swift/events","assignees_url":"https://api.github.com/repos/apple/swift/assignees{/user}","branches_url":"https://api.github.com/repos/apple/swift/branches{/branch}","tags_url":"https://api.github.com/repos/apple/swift/tags","blobs_url":"https://api.github.com/repos/apple/swift/git/blobs{/sha}","git_tags_url":"https://api.github.com/repos/apple/swift/git/tags{/sha}","git_refs_url":"https://api.github.com/repos/apple/swift/git/refs{/sha}","trees_url":"https://api.github.com/repos/apple/swift/git/trees{/sha}","statuses_url":"https://api.github.com/repos/apple/swift/statuses/{sha}","languages_url":"https://api.github.com/repos/apple/swift/languages","stargazers_url":"https://api.github.com/repos/apple/swift/stargazers","contributors_url":"https://api.github.com/repos/apple/swift/contributors","subscribers_url":"https://api.github.com/repos/apple/swift/subscribers","subscription_url":"https://api.github.com/repos/apple/swift/subscription","commits_url":"https://api.github.com/repos/apple/swift/commits{/sha}","git_commits_url":"https://api.github.com/repos/apple/swift/git/commits{/sha}","comments_url":"https://api.github.com/repos/apple/swift/comments{/number}","issue_comment_url":"https://api.github.com/repos/apple/swift/issues/comments{/number}","contents_url":"https://api.github.com/repos/apple/swift/contents/{+path}","compare_url":"https://api.github.com/repos/apple/swift/compare/{base}...{head}","merges_url":"https://api.github.com/repos/apple/swift/merges","archive_url":"https://api.github.com/repos/apple/swift/{archive_format}{/ref}","downloads_url":"https://api.github.com/repos/apple/swift/downloads","issues_url":"https://api.github.com/repos/apple/swift/issues{/number}","pulls_url":"https://api.github.com/repos/apple/swift/pulls{/number}","milestones_url":"https://api.github.com/repos/apple/swift/milestones{/number}","notifications_url":"https://api.github.com/repos/apple/swift/notifications{?since,all,participating}","labels_url":"https://api.github.com/repos/apple/swift/labels{/name}","releases_url":"https://api.github.com/repos/apple/swift/releases{/id}","deployments_url":"https://api.github.com/repos/apple/swift/deployments","created_at":"2015-10-23T21:15:07Z","updated_at":"2018-04-17T23:46:10Z","pushed_at":"2018-04-17T23:50:00Z","git_url":"git://github.com/apple/swift.git","ssh_url":"git@github.com:apple/swift.git","clone_url":"https://github.com/apple/swift.git","svn_url":"https://github.com/apple/swift","homepage":"https://swift.org/","size":280485,"stargazers_count":43404,"watchers_count":43404,"language":"C++","has_issues":false,"has_projects":false,"has_downloads":true,"has_wiki":false,"has_pages":false,"forks_count":6804,"mirror_url":null,"archived":false,"open_issues_count":302,"license":{"key":"apache-2.0","name":"Apache License 2.0","spdx_id":"Apache-2.0","url":"https://api.github.com/licenses/apache-2.0"},"forks":6804,"open_issues":302,"watchers":43404,"default_branch":"master"}},"_links":{"self":{"href":"https://api.github.com/repos/apple/swift/pulls/15999"},"html":{"href":"https://github.com/apple/swift/pull/15999"},"issue":{"href":"https://api.github.com/repos/apple/swift/issues/15999"},"comments":{"href":"https://api.github.com/repos/apple/swift/issues/15999/comments"},"review_comments":{"href":"https://api.github.com/repos/apple/swift/pulls/15999/comments"},"review_comment":{"href":"https://api.github.com/repos/apple/swift/pulls/comments{/number}"},"commits":{"href":"https://api.github.com/repos/apple/swift/pulls/15999/commits"},"statuses":{"href":"https://api.github.com/repos/apple/swift/statuses/29107fc30c24655abaebedc065fbb64616e75a06"}},"author_association":"CONTRIBUTOR"}}
{"actor":{"display_login":"jrose-apple"}}