RE: Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks.
Hi Satish I'm not sure about this, but it's a double Quad-Core CPU, each of them is Hyper Threading, so 14 mapper and 14 reducer for a node should be OK, right? I find each task finishs very quickly, no more than 20 seconds, so is this the root cause for this problem? ThanksRamon From: satish.se...@hcl.com To: mapreduce-user@hadoop.apache.org; ramon_w...@hotmail.com Date: Mon, 12 Mar 2012 09:00:49 +0530 Subject: RE: Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks. Just guessing if this has something to do with number of cores/cpus. Myself noticed this for number of map tasks spawned - depending on number of input files and also number of tasks to run concurrently depends on number cores/cpus. Thanks From: WangRamon [ramon_w...@hotmail.com] Sent: Saturday, March 10, 2012 5:35 PM To: mapreduce-user@hadoop.apache.org Subject: RE: Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks. Joey, here is the information: Cluster Summary (Heap Size is 481.88 MB/1.74 GB) Maps Reduces Total Submissions Nodes Map Task Capacity Reduce Task Capacity Avg. Tasks/Node Blacklisted Nodes 06 11 3 42 42 28.00 & nbsp; 0 Cheers Ramon Subject: Re: Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks. From: j...@cloudera.com Date: Sat, 10 Mar 2012 07:00:26 -0500 To: mapreduce-user@hadoop.apache.org What does the jobtracker web page say is the total reduce capacity? -Joey On Mar 10, 2012, at 5:39, WangRamon wrote: Hi All I'm using Hadoop-0.20-append, the cluster contains 3 nodes, for each node I have 14 map and 14 reduce slots, here is the configuration: mapred.tasktracker.map.tasks.maximum 14 mapred.tasktracker.reduce.tasks.maximum 14 mapred.reduce.tasks 73 When I submit 5 Jobs simultane ously (the input data for each job is not so big for the test, it's about 2~5M in size), I assume the Jobs will use the slots as much as possible, each Job did created 73 Reduce Tasks as configured above, so there will be 5 * 73 Reduce Tasks in total, but, most of them are in pending state, only about 12 of them are running, it's too small compared to the total slots number for reduce, 42 reduce slots for the 3 nodes cluster. What interestring is that it always about 12 of them are running, I tried a few times. So, I thought it might because about the scheduler, I changed it to Fair Scheduler, I created 3 pools, the configure is as below: 14 14 1.0 14 14 1.0 14 14 1.0 Then I submit the 5 Jobs simultaneously to these pools randomly again, I can see the jobs were assigned to different pools, but, it's still the same problem only about 12 of the reduce tasks from different pool are running, here is the output i copied from the Fair Scheduler monitor GUI: pool-a 2 14 14 0 9 pool-b 0 14 14 0 0 pool-c 2 14 14 0 3 pool-a and pool-c have a total of 12 reduce tasks running, but I do have about 11 reduce slots at least available in my cluster. So can anyone please give me some suggestions, why NOT all my REDUCE SLOTS are working? Thanks in advance. Cheers Ramon ::DISCLAIMER:: --- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. It shall not attach any liability on the originator or HCL or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any mail and attachments please check them for viruses and defect. ---
RE: Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks.
Joey, here is the information: Cluster Summary (Heap Size is 481.88 MB/1.74 GB)Maps Reduces Total Submissions Nodes Map Task Capacity Reduce Task Capacity Avg. Tasks/Node Blacklisted Nodes 06 11 3 42 42 28.00 0 CheersRamon Subject: Re: Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks. From: j...@cloudera.com Date: Sat, 10 Mar 2012 07:00:26 -0500 To: mapreduce-user@hadoop.apache.org What does the jobtracker web page say is the total reduce capacity? -Joey On Mar 10, 2012, at 5:39, WangRamon wrote: Hi All I'm using Hadoop-0.20-append, the cluster contains 3 nodes, for each node I have 14 map and 14 reduce slots, here is the configuration: mapred.tasktracker.map.tasks.maximum 14 mapred.tasktracker.reduce.tasks.maximum 14 mapred.reduce.tasks 73 When I submit 5 Jobs simultane ously (the input data for each job is not so big for the test, it's about 2~5M in size), I assume the Jobs will use the slots as much as possible, each Job did created 73 Reduce Tasks as configured above, so there will be 5 * 73 Reduce Tasks in total, but, most of them are in pending state, only about 12 of them are running, it's too small compared to the total slots number for reduce, 42 reduce slots for the 3 nodes cluster. What interestring is that it always about 12 of them are running, I tried a few times. So, I thought it might because about the scheduler, I changed it to Fair Scheduler, I created 3 pools, the configure is as below: 14 14 1.0 14 14 1.0 14 14 1.0 Then I submit the 5 Jobs simultaneously to these pools randomly again, I can see the jobs were assigned to different pools, but, it's still the same problem only about 12 of the reduce tasks from different pool are running, here is the output i copied from the Fair Scheduler monitor GUI: pool-a 2 14 14 0 9 pool-b 0 14 14 0 0 pool-c 2 14 14 0 3 pool-a and pool-c have a total of 12 reduce tasks running, but I do have about 11 reduce slots at least available in my cluster. So can anyone please give me some suggestions, why NOT all my REDUCE SLOTS are working? Thanks in advance. Cheers Ramon
Re: Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks.
What does the jobtracker web page say is the total reduce capacity? -Joey On Mar 10, 2012, at 5:39, WangRamon wrote: > Hi All > > I'm using Hadoop-0.20-append, the cluster contains 3 nodes, for each node I > have 14 map and 14 reduce slots, here is the configuration: > > > > mapred.tasktracker.map.tasks.maximum > 14 > > > mapred.tasktracker.reduce.tasks.maximum > 14 > > > mapred.reduce.tasks > 73 > > > > When I submit 5 Jobs simultane ously (the input data for each job is not so > big for the test, it's about 2~5M in size), I assume the Jobs will use the > slots as much as possible, each Job did created 73 Reduce Tasks as configured > above, so there will be 5 * 73 Reduce Tasks in total, but, most of them are > in pending state, only about 12 of them are running, it's too small compared > to the total slots number for reduce, 42 reduce slots for the 3 nodes > cluster. > > What interestring is that it always about 12 of them are running, I tried a > few times. > > So, I thought it might because about the scheduler, I changed it to Fair > Scheduler, I created 3 pools, the configure is as below: > > > > > 14 > 14 > 1.0 > > > 14 > 14 > 1.0 > > > 14 > 14 > 1.0 > > > > > Then I submit the 5 Jobs simultaneously to these pools randomly again, I can > see the jobs were assigned to different pools, but, it's still the same > problem only about 12 of the reduce tasks from different pool are running, > here is the output i copied from the Fair Scheduler monitor GUI: > > pool-a 2 14 14 0 9 > pool-b 0 14 14 0 0 > pool-c 2 14 14 0 3 > > pool-a and pool-c have a total of 12 reduce tasks running, but I do have > about 11 reduce slots at least available in my cluster. > > So can anyone please give me some suggestions, why NOT all my REDUCE SLOTS > are working? Thanks in advance. > > Cheers > Ramon
Why most of the free reduce slots are NOT used for my Hadoop Jobs? Thanks.
Hi All I'm using Hadoop-0.20-append, the cluster contains 3 nodes, for each node I have 14 map and 14 reduce slots, here is the configuration: mapred.tasktracker.map.tasks.maximum 14 mapred.tasktracker.reduce.tasks.maximum 14 mapred.reduce.tasks 73 When I submit 5 Jobs simultaneously (the input data for each job is not so big for the test, it's about 2~5M in size), I assume the Jobs will use the slots as much as possible, each Job did created 73 Reduce Tasks as configured above, so there will be 5 * 73 Reduce Tasks in total, but, most of them are in pending state, only about 12 of them are running, it's too small compared to the total slots number for reduce, 42 reduce slots for the 3 nodes cluster. What interestring is that it always about 12 of them are running, I tried a few times. So, I thought it might because about the scheduler, I changed it to Fair Scheduler, I created 3 pools, the configure is as below: 14 14 1.0 14 14 1.0 14 14 1.0 Then I submit the 5 Jobs simultaneously to these pools randomly again, I can see the jobs were assigned to different pools, but, it's still the same problem only about 12 of the reduce tasks from different pool are running, here is the output i copied from the Fair Scheduler monitor GUI: pool-a 2 14 14 0 9 pool-b 0 14 14 0 0 pool-c 2 14 14 0 3 pool-a and pool-c have a total of 12 reduce tasks running, but I do have about 11 reduce slots at least available in my cluster. So can anyone please give me some suggestions, why NOT all my REDUCE SLOTS are working? Thanks in advance. Cheers Ramon
