Return-Path: X-Original-To: apmail-hadoop-mapreduce-user-archive@minotaur.apache.org Delivered-To: apmail-hadoop-mapreduce-user-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 0F3D610442 for ; Tue, 17 Dec 2013 00:22:30 +0000 (UTC) Received: (qmail 15082 invoked by uid 500); 17 Dec 2013 00:22:25 -0000 Delivered-To: apmail-hadoop-mapreduce-user-archive@hadoop.apache.org Received: (qmail 14941 invoked by uid 500); 17 Dec 2013 00:22:25 -0000 Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@hadoop.apache.org Delivered-To: mailing list user@hadoop.apache.org Received: (qmail 14934 invoked by uid 99); 17 Dec 2013 00:22:24 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 17 Dec 2013 00:22:24 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of john.lilley@redpoint.net designates 206.225.164.233 as permitted sender) Received: from [206.225.164.233] (HELO hub021-nj-8.exch021.serverdata.net) (206.225.164.233) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 17 Dec 2013 00:22:16 +0000 Received: from MBX021-E3-NJ-2.exch021.domain.local ([10.240.4.78]) by HUB021-NJ-8.exch021.domain.local ([10.240.4.117]) with mapi id 14.03.0158.001; Mon, 16 Dec 2013 16:21:56 -0800 From: John Lilley To: "user@hadoop.apache.org" Subject: HDFS short-circuit reads Thread-Topic: HDFS short-circuit reads Thread-Index: Ac76vayamT7sZuxQTIi3YCeJL7BrCw== Date: Tue, 17 Dec 2013 00:21:54 +0000 Message-ID: <869970D71E26D7498BDAC4E1CA92226B86DF367D@MBX021-E3-NJ-2.exch021.domain.local> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [173.160.43.60] Content-Type: multipart/alternative; boundary="_000_869970D71E26D7498BDAC4E1CA92226B86DF367DMBX021E3NJ2exch_" MIME-Version: 1.0 X-Virus-Checked: Checked by ClamAV on apache.org --_000_869970D71E26D7498BDAC4E1CA92226B86DF367DMBX021E3NJ2exch_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Our YARN application would benefit from maximal bandwidth on HDFS reads. But I'm unclear on how short-circuit reads are enabled. Are they on by default? Can our application check programmatically to see if the short-circuit read= is enabled? Thanks, john RE: https://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/Shor= tCircuitLocalReads.html https://issues.apache.org/jira/browse/HDFS-347 --_000_869970D71E26D7498BDAC4E1CA92226B86DF367DMBX021E3NJ2exch_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Our YARN application would benefit from maximal band= width on HDFS reads.

But I’m unclear on how short-circuit reads are= enabled. 

Are they on by default? 

Can our application check programmatically to see if= the short-circuit read is enabled?

Thanks,

john=

 

RE:

https://hadoop.a= pache.org/docs/current/hadoop-project-dist/hadoop-hdfs/ShortCircuitLocalRea= ds.html

https://issues.apache.org/jira/browse/HDFS-347

 

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