Ok, DFS warnings problem solved, seems that hadoop-0.17.1 patch fixes the warnings... BUT, on a 7-node nutch cluster:
1) Fetching is only happening on *one* node despite several values tested on settings: mapred.tasktracker.map.tasks.maximum mapred.tasktracker.reduce.tasks.maximum export HADOOP_HEAPSIZE I've played with mapreduce (hadoop-site.xml) settings as advised on: http://wiki.apache.org/hadoop/HowManyMapsAndReduces But nutch keeps crawling only using one node, instead of seven nodes... anybody knows why ? I've had a look at the code, searching for: conf.setNumMapTasks(int num), but found none: so I guess that the number of mappers & reducers are not limited programatically. 2) Even on a single node, the fetching is really slow: 1 url or page per second, at most. Can anybody shed some light into this ? Pointing which class/code I should look into to modify this behaviour will help also. Anybody has a distributed nutch crawling cluster working with all nodes fetching at fetch phase ? I even did some numbers using wordcount example using 7 nodes at 100% cpu usage using a 425MB parsedtext file: maps reduces heapsize time 2 2 500 3m43.049s 4 4 500 4m41.846s 8 8 500 4m29.344s 16 16 500 3m43.672s 32 32 500 3m41.367s 64 64 500 4m27.275s 128 128 500 4m35.233s 256 256 500 3m41.916s 2 2 2000 4m31.434s 4 4 2000 8 8 2000 16 16 2000 4m32.213s 32 32 2000 64 64 2000 128 128 2000 256 256 2000 4m38.310s Thanks in advance, Roman On Tue, Jul 15, 2008 at 7:15 PM, brainstorm <[EMAIL PROTECTED]> wrote: > While seeing DFS wireshark trace (and the corresponding RST's), the > crawl continued to next step... seems that this WARNING is actually > slowing down the whole crawling process (it took 36 minutes to > complete the previous fetch) with just 3 urls seed file :-!!! > > I just posted a couple of exceptions/questions regarding DFS on hadoop > core mailing list. > > PD: As a side note, the following error caught my attention: > > Fetcher: starting > Fetcher: segment: crawl-ecxi/segments/20080715172458 > Too many fetch-failures > task_200807151723_0005_m_000000_0: Fetcher: threads: 10 > task_200807151723_0005_m_000000_0: fetching http://upc.es/ > task_200807151723_0005_m_000000_0: fetching http://upc.edu/ > task_200807151723_0005_m_000000_0: fetching http://upc.cat/ > task_200807151723_0005_m_000000_0: fetch of http://upc.cat/ failed > with: org.apache.nutch.protocol.http.api.HttpException: > java.net.UnknownHostException: upc.cat > > Unknown host ?¿ Just try "http://upc.cat"; on your browser, it *does* > exist, it just gets redirected to www.upc.cat :-/ > > On Tue, Jul 15, 2008 at 5:42 PM, brainstorm <[EMAIL PROTECTED]> wrote: >> Yep, I know about wireshark, and wanted to avoid it to debug this >> issue (perhaps there was a simple solution/known bug/issue)... >> >> I just launched wireshark on frontend with filter tcp.port == 50010, >> and now I'm diving on the tcp stream... let's see if I see the light >> (RST flag somewhere ?), thanks anyway for replying ;) >> >> Just for the record, the phase that stalls is fetcher during reduce: >> >> Jobid User Name Map % Complete Map Total Maps Completed >> Reduce % >> Complete Reduce Total Reduces Completed >> job_200807151723_0005 hadoop fetch crawl-ecxi/segments/20080715172458 >> 100.00% >> 2 2 16.66% >> >> 1 0 >> >> It's stuck on 16%, no traffic, no crawling, but still "running". >> >> On Tue, Jul 15, 2008 at 4:28 PM, Patrick Markiewicz >> <[EMAIL PROTECTED]> wrote: >>> Hi brain, >>> If I were you, I would download wireshark >>> (http://www.wireshark.org/download.html) to see what is happening at the >>> network layer and see if that provides any clues. A socket exception >>> that you don't expect is usually due to one side of the conversation not >>> understanding the other side. If you have 4 machines, then you have 4 >>> possible places where default firewall rules could be causing an issue. >>> If it is not the firewall rules, the NAT rules could be a potential >>> source of error. Also, even a router hardware error could cause a >>> problem. >>> If you understand TCP, just make sure that you see all the >>> correct TCP stuff happening in wireshark. If you don't understand >>> wireshark's display, let me know, and I'll pass on some quickstart >>> information. >>> >>> If you already know all of this, I don't have any way to help >>> you, as it looks like you're trying to accomplish something trickier >>> with nutch than I have ever attempted. >>> >>> Patrick >>> >>> -----Original Message----- >>> From: brainstorm [mailto:[EMAIL PROTECTED] >>> Sent: Tuesday, July 15, 2008 10:08 AM >>> To: [email protected] >>> Subject: Re: Distributed fetching only happening in one node ? >>> >>> Boiling down the problem I'm stuck on this: >>> >>> 2008-07-14 16:43:24,976 WARN dfs.DataNode - >>> 192.168.0.100:50010:Failed to transfer blk_-855404545666908011 to >>> 192.168.0.252:50010 got java.net.SocketException: Connection reset >>> at >>> java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:96) >>> at >>> java.net.SocketOutputStream.write(SocketOutputStream.java:136) >>> at >>> java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65) >>> at >>> java.io.BufferedOutputStream.write(BufferedOutputStream.java:109) >>> at java.io.DataOutputStream.write(DataOutputStream.java:90) >>> at >>> org.apache.hadoop.dfs.DataNode$BlockSender.sendChunk(DataNode.java:1602) >>> at >>> org.apache.hadoop.dfs.DataNode$BlockSender.sendBlock(DataNode.java:1636) >>> at >>> org.apache.hadoop.dfs.DataNode$DataTransfer.run(DataNode.java:2391) >>> at java.lang.Thread.run(Thread.java:595) >>> >>> Checked that firewall settings between node & frontend were not >>> blocking packets, and they don't... anyone knows why is this ? If not, >>> could you provide a convenient way to debug it ? >>> >>> Thanks ! >>> >>> On Sun, Jul 13, 2008 at 3:41 PM, brainstorm <[EMAIL PROTECTED]> wrote: >>>> Hi, >>>> >>>> I'm running nutch+hadoop from trunk (rev) on a 4 machine rocks >>>> cluster: 1 frontend doing NAT to 3 leaf nodes. I know it's not the >>>> best suited network topology for inet crawling (frontend being a net >>>> bottleneck), but I think it's fine for testing purposes. >>>> >>>> I'm having issues with fetch mapreduce job: >>>> >>>> According to ganglia monitoring (network traffic), and hadoop >>>> administrative interfaces, fetch phase is only being executed in the >>>> frontend node, where I launched "nutch crawl". Previous nutch phases >>>> were executed neatly distributed on all nodes: >>>> >>>> job_200807131223_0001 hadoop inject urls 100.00% >>>> 2 2 100.00% >>>> 1 1 >>>> job_200807131223_0002 hadoop crawldb crawl-ecxi/crawldb >>> 100.00% >>>> 3 3 100.00% >>>> 1 1 >>>> job_200807131223_0003 hadoop generate: select >>>> crawl-ecxi/segments/20080713123547 100.00% >>>> 3 3 100.00% >>>> 1 1 >>>> job_200807131223_0004 hadoop generate: partition >>>> crawl-ecxi/segments/20080713123547 100.00% >>>> 4 4 100.00% >>>> 2 2 >>>> >>>> I've checked that: >>>> >>>> 1) Nodes have inet connectivity, firewall settings >>>> 2) There's enough space on local discs >>>> 3) Proper processes are running on nodes >>>> >>>> frontend-node: >>>> ========== >>>> >>>> [EMAIL PROTECTED] ~]# jps >>>> 29232 NameNode >>>> 29489 DataNode >>>> 29860 JobTracker >>>> 29778 SecondaryNameNode >>>> 31122 Crawl >>>> 30137 TaskTracker >>>> 10989 Jps >>>> 1818 TaskTracker$Child >>>> >>>> leaf nodes: >>>> ======== >>>> >>>> [EMAIL PROTECTED] ~]# cluster-fork jps >>>> compute-0-1: >>>> 23929 Jps >>>> 15568 TaskTracker >>>> 15361 DataNode >>>> compute-0-2: >>>> 32272 TaskTracker >>>> 32065 DataNode >>>> 7197 Jps >>>> 2397 TaskTracker$Child >>>> compute-0-3: >>>> 12054 DataNode >>>> 19584 Jps >>>> 14824 TaskTracker$Child >>>> 12261 TaskTracker >>>> >>>> 4) Logs only show fetching process (taking place only in the head >>> node): >>>> >>>> 2008-07-13 13:33:22,306 INFO fetcher.Fetcher - fetching >>>> http://valleycycles.net/ >>>> 2008-07-13 13:33:22,349 INFO api.RobotRulesParser - Couldn't get >>>> robots.txt for http://www.getting-forward.org/: >>>> java.net.UnknownHostException: www.getting-forward.org >>>> 2008-07-13 13:33:22,349 INFO api.RobotRulesParser - Couldn't get >>>> robots.txt for http://www.getting-forward.org/: >>>> java.net.UnknownHostException: www.getting-forward.org >>>> >>>> What am I missing ? Why there are no fetching instances on nodes ? I >>>> used the following custom script to launch a pristine crawl each time: >>>> >>>> #!/bin/sh >>>> >>>> # 1) Stops hadoop daemons >>>> # 2) Overwrites new url list on HDFS >>>> # 3) Starts hadoop daemons >>>> # 4) Performs a clean crawl >>>> >>>> #export JAVA_HOME=/usr/lib/jvm/java-6-sun >>>> export JAVA_HOME=/usr/java/jdk1.5.0_10 >>>> >>>> CRAWL_DIR=crawl-ecxi || $1 >>>> URL_DIR=urls || $2 >>>> >>>> echo $CRAWL_DIR >>>> echo $URL_DIR >>>> >>>> echo "Leaving safe mode..." >>>> ./hadoop dfsadmin -safemode leave >>>> >>>> echo "Removing seed urls directory and previous crawled content..." >>>> ./hadoop dfs -rmr $URL_DIR >>>> ./hadoop dfs -rmr $CRAWL_DIR >>>> >>>> echo "Removing past logs" >>>> >>>> rm -rf ../logs/* >>>> >>>> echo "Uploading seed urls..." >>>> ./hadoop dfs -put ../$URL_DIR $URL_DIR >>>> >>>> #echo "Entering safe mode..." >>>> #./hadoop dfsadmin -safemode enter >>>> >>>> echo "******************" >>>> echo "* STARTING CRAWL *" >>>> echo "******************" >>>> >>>> ./nutch crawl $URL_DIR -dir $CRAWL_DIR -depth 3 >>>> >>>> >>>> Next step I'm thinking on to fix the problem is to install >>>> nutch+hadoop as specified in this past nutch-user mail: >>>> >>>> http://www.mail-archive.com/[email protected]/msg10225.html >>>> >>>> As I don't know if it's current practice on trunk (archived mail is >>>> from Wed, 02 Jan 2008), I wanted to ask if there's another way to fix >>>> it or if it's being worked on by someone... I haven't found a matching >>>> bug on JIRA :_/ >>>> >>> >> >
