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Diffstat (limited to 'docs/configuration.md')
-rw-r--r-- | docs/configuration.md | 49 |
1 files changed, 32 insertions, 17 deletions
diff --git a/docs/configuration.md b/docs/configuration.md index fa7123af1b..db90b5bc16 100644 --- a/docs/configuration.md +++ b/docs/configuration.md @@ -113,36 +113,43 @@ Apart from these, the following properties are also available, and may be useful </td> </tr> <tr> - <td>spark.blockManager.compress</td> - <td>false</td> + <td>spark.storage.memoryFraction</td> + <td>0.66</td> + <td> + Fraction of Java heap to use for Spark's memory cache. This should not be larger than the "old" + generation of objects in the JVM, which by default is given 2/3 of the heap, but you can increase + it if you configure your own old generation size. + </td> +</tr> +<tr> + <td>spark.shuffle.compress</td> + <td>true</td> <td> - Set to "true" to have Spark compress map output files, RDDs that get cached on disk, - and RDDs that get cached in serialized form. Generally a good idea when dealing with - large datasets, but might add some CPU overhead. + Whether to compress map output files. Generally a good idea. </td> </tr> <tr> <td>spark.broadcast.compress</td> - <td>false</td> + <td>true</td> <td> - Set to "true" to have Spark compress broadcast variables before sending them. - Generally a good idea when broadcasting large values. + Whether to compress broadcast variables before sending them. Generally a good idea. </td> </tr> <tr> - <td>spark.storage.memoryFraction</td> - <td>0.66</td> + <td>spark.rdd.compress</td> + <td>false</td> <td> - Fraction of Java heap to use for Spark's memory cache. This should not be larger than the "old" - generation of objects in the JVM, which by default is given 2/3 of the heap, but you can increase - it if you configure your own old generation size. + Whether to compress serialized RDD partitions (e.g. for <code>StorageLevel.MEMORY_ONLY_SER</code>). + Can save substantial space at the cost of some extra CPU time. </td> </tr> <tr> - <td>spark.blockManager.parallelFetches</td> - <td>4</td> + <td>spark.reducer.maxMbInFlight</td> + <td>48</td> <td> - Number of map output files to fetch concurrently from each reduce task. + Maximum size (in megabytes) of map outputs to fetch simultaneously from each reduce task. Since + each output requires us to create a buffer to receive it, this represents a fixed memory overhead + per reduce task, so keep it small unless you have a large amount of memory. </td> </tr> <tr> @@ -179,10 +186,18 @@ Apart from these, the following properties are also available, and may be useful </td> </tr> <tr> + <td>spark.akka.threads</td> + <td>4</td> + <td> + Number of actor threads to use for communication. Can be useful to increase on large clusters + when the master has a lot of CPU cores. + </td> +</tr> +<tr> <td>spark.master.host</td> <td>(local hostname)</td> <td> - Hostname for the master to listen on (it will bind to this hostname's IP address). + Hostname or IP address for the master to listen on. </td> </tr> <tr> |