{"action":"created","issue":{"url":"https://api.github.com/repos/dotnet/coreclr/issues/15629","repository_url":"https://api.github.com/repos/dotnet/coreclr","labels_url":"https://api.github.com/repos/dotnet/coreclr/issues/15629/labels{/name}","comments_url":"https://api.github.com/repos/dotnet/coreclr/issues/15629/comments","events_url":"https://api.github.com/repos/dotnet/coreclr/issues/15629/events","html_url":"https://github.com/dotnet/coreclr/pull/15629","id":284342842,"number":15629,"title":"Reduce EC Save+Restore for Default context","user":{"login":"benaadams","id":1142958,"avatar_url":"https://avatars1.githubusercontent.com/u/1142958?v=4","gravatar_id":"","url":"https://api.github.com/users/benaadams","html_url":"https://github.com/benaadams","followers_url":"https://api.github.com/users/benaadams/followers","following_url":"https://api.github.com/users/benaadams/following{/other_user}","gists_url":"https://api.github.com/users/benaadams/gists{/gist_id}","starred_url":"https://api.github.com/users/benaadams/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/benaadams/subscriptions","organizations_url":"https://api.github.com/users/benaadams/orgs","repos_url":"https://api.github.com/users/benaadams/repos","events_url":"https://api.github.com/users/benaadams/events{/privacy}","received_events_url":"https://api.github.com/users/benaadams/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":6,"created_at":"2017-12-24T04:52:42Z","updated_at":"2017-12-27T21:17:05Z","closed_at":null,"author_association":"CONTRIBUTOR","pull_request":{"url":"https://api.github.com/repos/dotnet/coreclr/pulls/15629","html_url":"https://github.com/dotnet/coreclr/pull/15629","diff_url":"https://github.com/dotnet/coreclr/pull/15629.diff","patch_url":"https://github.com/dotnet/coreclr/pull/15629.patch"},"body":"x 1.58 speed up for `ExecutionContext.Run(ec, (o) => { }, null);` where `ec == Default`\r\n\r\nAlternative approach to https://github.com/dotnet/coreclr/pull/11100 as suggested by @kouvel https://github.com/dotnet/coreclr/pull/11100#discussion_r113028941\r\n\r\nWhen `Default` context is used in `Run` use it as `null`; which also counts as Default - rather than having two forms of `Default` context internally (Thread starts will null) and saving and restoring between them.\r\n\r\n```\r\n Method |   Current |       New |    Change |\r\n------- |----------:|----------:|----------:|\r\n    Run | 14.690 ns |  9.263 ns |    x 1.58 |\r\n```\r\n\r\nPrevious call tracing\r\n![image](https://user-images.githubusercontent.com/1142958/34344008-fe137eb0-e9d7-11e7-948e-5f78b3d99875.png)\r\n\r\nPost call tracing (`Restore` not invoked)\r\n![image](https://user-images.githubusercontent.com/1142958/34344012-08d400c2-e9d8-11e7-9325-d1ee860ede0e.png)\r\n\r\n\r\nResolves #11126 \r\n\r\nWill need corresponding corert changes to non-shared AsyncMethodBuilder/Thread  https://github.com/dotnet/corert/pull/5153\r\n"},"comment":{"url":"https://api.github.com/repos/dotnet/coreclr/issues/comments/354178884","html_url":"https://github.com/dotnet/coreclr/pull/15629#issuecomment-354178884","issue_url":"https://api.github.com/repos/dotnet/coreclr/issues/15629","id":354178884,"user":{"login":"benaadams","id":1142958,"avatar_url":"https://avatars1.githubusercontent.com/u/1142958?v=4","gravatar_id":"","url":"https://api.github.com/users/benaadams","html_url":"https://github.com/benaadams","followers_url":"https://api.github.com/users/benaadams/followers","following_url":"https://api.github.com/users/benaadams/following{/other_user}","gists_url":"https://api.github.com/users/benaadams/gists{/gist_id}","starred_url":"https://api.github.com/users/benaadams/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/benaadams/subscriptions","organizations_url":"https://api.github.com/users/benaadams/orgs","repos_url":"https://api.github.com/users/benaadams/repos","events_url":"https://api.github.com/users/benaadams/events{/privacy}","received_events_url":"https://api.github.com/users/benaadams/received_events","type":"User","site_admin":false},"created_at":"2017-12-27T21:17:04Z","updated_at":"2017-12-27T21:17:04Z","author_association":"CONTRIBUTOR","body":"PTAL @stephentoub "}}
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