{"id":463,"date":"2019-08-16T11:56:17","date_gmt":"2019-08-16T03:56:17","guid":{"rendered":"https:\/\/himmel.tech\/wp\/?p=463"},"modified":"2019-08-16T11:56:17","modified_gmt":"2019-08-16T03:56:17","slug":"%e8%af%b4%e8%af%b4-github-com-pkg-sftp-%e4%b8%8e-tcp-stall","status":"publish","type":"post","link":"https:\/\/himmel.tech\/wp\/?p=463","title":{"rendered":"\u8bf4\u8bf4 github.com\/pkg\/sftp \u4e0e TCP stall"},"content":{"rendered":"\n

\u597d\u4e45\u6ca1\u5199\u8fc7\u4e1c\u897f\u4e86\uff0c\u6700\u8fd1\u4e00\u76f4\u5728\u6298\u817e Golang\uff0c\u4eca\u5929\u96be\u5f97\u60f3\u8d77\u6765\u4e86\uff0c\u5c31\u7a0d\u5fae\u5199\u4e00\u70b9\u3002<\/p>\n\n\n\n

\u6700\u8fd1\u6709\u4e2a\u9700\u6c42\uff0c\u8981\u901a\u8fc7 SFTP \u628a\u6587\u4ef6\u4f20\u5230\u6307\u5b9a\u670d\u52a1\u5668\u4e0a\uff0c\u4e8e\u662f\u5c31\u7528\u4e86 github.com\/pkg\/sftp \u8fd9\u4e48\u4e00\u4e2a\u5e93\u3002\u7136\u800c\uff0c\u8fd9\u4e2a\u5e93\u5b58\u662f\u5b58\u5728\u4e00\u4e9b\u5751\u7684\uff0c\u6bd4\u5982\u67d0\u4e2a\u7248\u672c sftp.File.Write \u5199\u8d85\u8fc7 4MiB \u7684\u6587\u4ef6\u65f6\uff0cKill \u8fdc\u7a0b sshd \u540e\u4f1a\u5bfc\u81f4 Close \u65f6\u6b7b\u9501\uff1b\u53c8\u6bd4\u5982\u66f4\u65b0\u4ee3\u7801\u540e\uff0cKill \u4e86\u8fdc\u7aef\u4e4b\u540e\u6709\u65f6 ReadFrom \u8fd4\u56de Writer EOF\uff0c\u6709\u65f6\u8fd4\u56de nil\uff1b\u518d\u6bd4\u5982\u6a21\u62df\u5f31\u7f51\u65f6\u53d1\u751f\u4e86 TCP Stall\uff0c\u4f20\u8f93\u5c31\u6c38\u8fdc\u7684\u5361\u6b7b\u4e86\uff0c\u5982\u679c\u6b64\u65f6\u5bf9\u7aef\u8ba4\u4e3a TCP \u8d85\u65f6\uff0c\u5219\u8be5 TCP \u5c06\u6c38\u8fdc\u4e0d\u4f1a\u88ab\u91ca\u653e\u3002<\/p>\n\n\n\n\n\n\n\n

RTT \u95ee\u9898<\/h2>\n\n\n\n

\u6700\u521d\u7684\u4e00\u7248\uff0c\u4e3a\u4e86\u5b9e\u73b0\u4f20\u8f93\u65f6\u7684\u8fdb\u5ea6\u62a5\u544a\u548c\u8d85\u65f6\uff0c\u6211\u5199\u51fa\u4e86\u8fd9\u6837\u7684\u4ee3\u7801\uff1a<\/p>\n\n\n\n

buf := make([]byte, 64 << 10)\nn, _ := fr.Read(buf)\n_, _ := fw.Write(buf[1:n])<\/code><\/pre>\n\n\n\n
\u5728\u6d4b\u8bd5\u73af\u5883\u4e0b\uff0c\u8fd9\u4e00\u5207\u770b\u8d77\u6765\u90fd\u5f88\u597d\uff0c\u7ebf\u4e0a\u8868\u73b0\u4e00\u76f4\u4e5f\u5f88\u6b63\u5e38\uff0c\u76f4\u5230\u67d0\u5929\u53d1\u73b0\u6709\u4e00\u4e9b\u6d77\u5916\u673a\u5668\u4f20\u8f93\u5947\u6162\uff0c\u4f46\u7528 scp \u547d\u4ee4\u5219\u6ca1\u8fd9\u6bdb\u75c5\u3002\u5f53\u65f6\u767e\u601d\u4e0d\u5f97\u5176\u89e3\uff0c\u76f4\u5230\u6211 ping \u4e86\u4e00\u4e0b\uff0c\u53d1\u73b0\u5ef6\u8fdf\u8db3\u8db3\u6709 400ms \uff01<\/p>\n\n\n\n
\u90a3\u4e48\u8fd9\u4f1a\u6709\u4ec0\u4e48\u95ee\u9898\u5462\uff1f\u8fd9\u4e2a sftp.File.Write() \u4f1a\u5199\u5165\u6587\u4ef6\uff0c\u7136\u540e\u62a5\u544a\u5199\u5165\u5b57\u8282\u6570\u3002\u90a3\u4e48\u8fd9\u4e2a\u5b57\u8282\u6570\u548c\u9519\u8bef\u600e\u4e48\u6765\u7684\u5462\uff1f\u662f\u4e0d\u662f\u8981\u5bf9\u7aef\u62a5\u544a\uff1f\u6240\u6709\u5728 400ms \u5ef6\u8fdf\u7684\u7f51\u7edc\u4e0a\uff0c\u5199\u5165\u901f\u7387\u7406\u8bba\u4e0a\u6491\u6b7b\u4e5f\u53ea\u80fd\u8dd1\u5230<\/p>\n\n\n\n
1s \/ 400ms * 32 KiB = 160 KiB\/s<\/code><\/pre>\n\n\n\n
\u5b9e\u9645\u4e0a\u4f20\u8f93\u901f\u5ea6\u786e\u5b9e\u4e5f\u5728\u8fd9\u4e2a\u6c34\u5e73\u3002\u90a3\u4e48\u8fd9\u4e2a\u95ee\u9898\u8981\u5982\u4f55\u89e3\u51b3\u5462\uff1f\u6700\u7b80\u5355\u7684\u662f\u589e\u5927\u7f13\u51b2\u5927\u5c0f\uff0c\u4f46\u663e\u7136\u8fd9\u6cbb\u6807\u4e0d\u6cbb\u672c\u3002\u7406\u60f3\u7684\u65b9\u5f0f\u662f\u5141\u8bb8\u4e00\u90e8\u5206\u6570\u636e on the fly\uff0c\u5c31\u50cf TCP \u7684\u6ed1\u52a8\u7a97\u53e3\u673a\u5236\u4e00\u6837\u3002\u5b9e\u9645\u4e0a Write \u51fd\u6570\u5185\u90e8\u4e5f\u662f\u8fd9\u4e48\u505a\u7684\uff0c\u5b83\u628a\u8981\u53d1\u9001\u7684\u5185\u5bb9\u5207\u6210 32 KiB \u957f\u7684\u7247\u6bb5\uff0c\u6700\u591a\u5141\u8bb8 64 \u4e2a\u7247\u6bb5 on the fly\uff0c\u6b64\u65f6\u7406\u8bba\u4f20\u8f93\u901f\u5ea6\u80fd\u591f\u8fbe\u5230 10 MiB\/s\uff0c\u5927\u5927\u6539\u5584\u4e86\u8fd9\u79cd\u60c5\u51b5\u3002\u56e0\u6b64\u6211\u4eec\u9700\u8981\u7528 sftp.File.ReadFrom() \u8fd9\u4e00\u51fd\u6570\uff0c\u4f46\u8fd9\u4e00\u51fd\u6570\u53c8\u8981\u600e\u4e48\u6c47\u62a5\u8fdb\u5ea6\u5462\uff1f\u53c8\u600e\u4e48\u5904\u7406\u8d85\u65f6\uff1f<\/p>\n\n\n\n
\u8fd9\u91cc\u6211\u628a Reader \u5305\u88c5\u4e86\u4e00\u5c42\uff0c\u5305\u8fdb\u53bb\u4e86\u4e00\u4e2a\u7ba1\u9053\u548c\u4e00\u4e2a\u8ba1\u6570\u5668\uff0c\u5f53\u8c03\u7528 Read \u65f6\uff0c\u5b83\u5148\u6267\u884c\u8d85\u65f6\u68c0\u67e5\uff0c\u968f\u540e\u8bfb\u53d6\u3001\u7d2f\u52a0\u8ba1\u6570\u5668\u3001\u5199\u7ba1\u9053\uff0c\u6700\u540e\u8fd4\u56de Read \u7684\u7ed3\u679c\u3002\u663e\u7136\u6b64\u65f6\u7684\u8fdb\u5ea6\u663e\u793a\u7684\u662f\u5df2\u7ecf\u8bfb\u53d6\u7684\u5b57\u8282\u6570\uff0c\u800c\u4e0d\u662f\u5df2\u5199\u5165\u7684\u5b57\u8282\u6570\uff0c\u4e0d\u8fc7\u4e00\u822c\u60c5\u51b5\u4e0b\u8fd9\u5e76\u4e0d\u9020\u6210\u95ee\u9898\u3002<\/p>\n\n\n\n
\u6a21\u62df 400ms \u5ef6\u8fdf\u7684\u5f31\u7f51\u4e0b\uff0c\u8be5\u95ee\u9898\u786e\u5b9e\u5f97\u5230\u4e86\u89e3\u51b3\uff0c\u8dd1\u5f97\u98de\u5feb\u3002<\/p>\n\n\n\n
PS. \u5176\u5b9e\u4e5f\u8003\u8651\u8fc7 io.Pipe()\uff0c\u4f46\u90a3\u6837\u9519\u8bef\u4f20\u64ad\u4f1a\u53d8\u5f97\u5f88\u9ebb\u70e6\uff0c\u4ee3\u7801\u770b\u8d77\u6765\u5f88\u4e71\u3002<\/p>\n\n\n\n
TCP Stall<\/h2>\n\n\n\n
\u90a3\u4e48\uff0c\u95ee\u9898\u5168\u90e8\u89e3\u51b3\u4e86\u5417\uff1f\u89e3\u51b3\u4e86\uff0c\u4f46\u5f15\u5165\u4e86\u65b0\u7684\u95ee\u9898\u3002<\/p>\n\n\n\n
\u4e3a\u4e86\u6d4b\u8bd5\u8d85\u65f6\u7684\u60c5\u51b5\uff0c\u6211\u6a21\u62df\u4e86\u4e00\u4e2a\u8d85\u7ea7\u5927\u5f31\u7f51\u3002\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4f20\u8f93\u534f\u7a0b\u4f1a\u5f7b\u5e95\u5361\u6b7b\uff0c\u7531\u4e8e ReadFrom \u64cd\u4f5c\u4e0d\u8fd4\u56de\uff0c\u90a3\u4e48 Context \u91cc\u9762\u7684 DeadLine \u4e5f\u4e0d\u8d77\u4f5c\u7528\u3002\u66f4\u4e25\u91cd\u7684\u662f\uff0c\u8d77\u4e00\u4e2a goroutine \u8d85\u65f6\u540e sftp.File.Close \u8fd9\u4e00\u5957\u8def\u4e5f\u4e0d\u7ba1\u7528\uff0c\u56e0\u4e3a Close \u4e5f\u4f1a\u4e00\u8d77\u5361\u6b7b\u3002<\/p>\n\n\n\n
\u6b64\u65f6\u5982\u679c\u975e\u5e38\u4e0d\u5e78\uff0c\u5bf9\u65b9\u53d1\u751f\u4e86\u91cd\u542f\uff0c\u6216\u8005\u5bf9\u65b9\u7684 TCP \u8fde\u63a5\u8d85\u65f6\uff0c\u95ee\u9898\u4f1a\u66f4\u52a0\u4e25\u91cd\u3002\u5728\u6d4b\u8bd5\u4e2d\uff0c\u8be5 TCP \u8fde\u63a5\u5373\u4f7f 12hrs \u540e\u4e5f\u672a\u8d85\u65f6\uff0c\u4e00\u76f4\u5904\u4e8e ESTABLISHED \u7684\u72b6\u6001\u800c\u4e0d\u4f1a\u91ca\u653e\u3002<\/p>\n\n\n\n
\u4e00\u5f00\u59cb\u6211\u5bf9\u8fd9\u79cd\u60c5\u51b5\u975e\u5e38\u56f0\u60d1\uff0c\u76f4\u5230\u6211\u62ff scp \u547d\u4ee4\u8bd5\u4e86\u4e00\u4e0b\uff0cscp \u547d\u4ee4\u4e5f\u5361\u6b7b\u4e86\uff0c\u5e76\u63d0\u793a TCP stalled\u3002\u770b\u5230\u8fd9\u91cc\u4e00\u4e0b\u5b50\u5c31\u660e\u767d\u4e86\uff0c\u662f\u5e95\u5c42 TCP \u51fa\u73b0\u4e86\u95ee\u9898\u3002\u8fd8\u8bb0\u5f97 TCP \u7684\u6ed1\u52a8\u7a97\u53e3\u673a\u5236\u5417\uff1fTCP \u4e5f\u662f\u5141\u8bb8\u6709\u4e00\u90e8\u5206\u6570\u636e on the fly\uff0c\u4f46\u4e00\u65e6\u8fd9\u4e2a\u7a97\u53e3\u7528\u5c3d\uff0cTCP \u5c31\u4f1a\u50bb\u7b49 ACK\u3002\u5728\u4e0d\u8003\u8651 KeepAlive \u7684\u60c5\u51b5\u4e0b\uff0c\u5982\u679c\u5bf9\u7aef\u628a\u8fd9\u4e2a TCP \u8fde\u63a5\u5173\u4e86\uff0c\u800c FIN \u53c8\u4e0d\u5e78\u4e22\u6389\u4e86\uff0c\u90a3\u4e48\u8fd9\u4e2a\u8fde\u63a5\u5373\u4e0d\u4f1a\u6536\u5230\u4efb\u4f55\u6570\u636e\uff0c\u4e5f\u4e0d\u4f1a\u518d\u53d1\u9001\u4efb\u4f55\u6570\u636e\uff08\u610f\u5473\u7740\u4e0d\u4f1a\u6536\u5230 REJECT \u4ece\u800c\u53d1\u73b0\u95ee\u9898\uff09\uff0c\u6c38\u8fdc\u5904\u4e8e TCP Stalled \u72b6\u6001\u5e76\u65e0\u6cd5\u6062\u590d\u3002<\/p>\n\n\n\n
\u90a3\u4e48 golang.org\/x\/crypto\/ssh \u5728\u5efa\u7acb\u8fde\u63a5\u65f6\u9ed8\u8ba4\u6709\u5e2e\u6211\u4eec\u6253\u5f00 KeepAlive \u5417\uff1f\u5f88\u9057\u61be\u5e76\u6ca1\u6709\uff0c\u56e0\u6b64\u6211\u628a\u5b83\u7684 DialTimeout \u51fd\u6570\u6539\u4e86\u4e00\u4e2a\u672c\u5730\u7248\u672c\u51fa\u6765\uff0c\u5728 net.Dial \u4e4b\u540e\u4e3a\u8fde\u63a5\u8bbe\u7f6e\u4e86 5s \u7684 KeepAlive\u3002\u53e6\u5916\u6211\u8fd8\u7528\u4e86 SetDeadline \u8fd9\u6837\u66f4\u6fc0\u8fdb\u7684\u7b56\u7565\uff0c\u4fdd\u8bc1\u8be5\u8fde\u63a5\u80fd\u591f\u6b63\u5e38\u5173\u65ad\uff0c\u987a\u4fbf\u66ff\u4ee3\u903b\u8f91\u5c42\u7684\u8d85\u65f6\u68c0\u67e5\u3002\u6d4b\u8bd5\u8868\u660e\uff0c\u5f88\u597d\u7528\u3002<\/p>\n\n\n\n
\u56e0\u6b64\uff0c\u5bf9\u4e8e\u4e00\u4e2a\u670d\u52a1\u7aef\u7a0b\u5e8f\uff0c\u603b\u662f\u4e3a\u5404\u79cd\u77ed\u8fde\u63a5\u8bbe\u7f6e Deadline \u662f\u4e00\u4e2a\u4e0d\u9519\u7684\u9009\u62e9\uff0c\u957f\u8fde\u63a5\u5219\u5e94\u8be5\u628a KeepAlive \u6253\u5f00\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u597d\u4e45\u6ca1\u5199\u8fc7\u4e1c\u897f\u4e86\uff0c\u6700\u8fd1\u4e00\u76f4\u5728\u6298\u817e Golang\uff0c\u4eca\u5929\u96be\u5f97\u60f3\u8d77\u6765\u4e86\uff0c\u5c31\u7a0d\u5fae\u5199\u4e00\u70b9\u3002 \u6700\u8fd1\u6709\u4e2a\u9700\u6c42\uff0c\u8981\u901a\u8fc7 SFT … <\/p>\n
\u7ee7\u7eed\u9605\u8bfb\u201c\u8bf4\u8bf4 github.com\/pkg\/sftp \u4e0e TCP stall\u201d<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1],"tags":[],"class_list":["post-463","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p83CFH-7t","_links":{"self":[{"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=\/wp\/v2\/posts\/463","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=463"}],"version-history":[{"count":2,"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=\/wp\/v2\/posts\/463\/revisions"}],"predecessor-version":[{"id":465,"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=\/wp\/v2\/posts\/463\/revisions\/465"}],"wp:attachment":[{"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=463"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=463"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/himmel.tech\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=463"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}