track.performance(track)
track.performance()所属R语言包：track
Performance tuning with track.
性能优化轨道。
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Performance tuning with track involves trading off memory use for faster access times to objects. Access time is fastest when all objects are cached in memory, but memory can be exhausted if this is done. Memory use is minimized when objects are not cached in memory at all, but then a file must be read or written each time an object is referenced, and the whole file must be read or written even if only a small part of the object is actually used or changed.
断电记忆功能的使用性能优化与跟踪，涉及买卖的对象为更快的访问时间。访问时间是最快的，当所有的对象都是在内存中缓存，但如果这样做，可以被耗尽内存。对象时，不会被缓存在内存中，内存使用量最小化，但文件必须被读取或写入每次被引用的对象，必须读取整个文件或书面的，即使只有一小部分的对象实际上是使用或改变。
The default mode of operation of track balances memory use and access times by keeping objects in memory for the duration of a top-level task, and flushing them out at the end of the task.
的默认模式运行的轨道平衡的内存使用和访问时间，对象在内存中的顶级任务的持续时间，并在任务结束后冲洗出来。
Three options (see track.options) control performance:
cache: TRUE/FALSE should variables be cached at all?
缓存：TRUE / FALSE应变量缓存呢？
cachePolicy: tltPurge/none higher level policy for maintaining cache
cachePolicy：tltPurge/none更高层次的政策保持高速缓存
writeToDisk: TRUE/FALSE should objects be written after a change?
writeToDisk：TRUE/FALSE应该改变对象后写？
Useful possible combinations of settings are:
可能的组合设置是：
cache=TRUE, cachePolicy="tltPurge", writeToDisk=TRUE: (DEFAULT) keep objects in memory for the duration of a task; flush and/or write to disk at the end of task
缓存= TRUE，cachePolicy的“tltPurge”，writeToDisk = TRUE：（默认）保持内存中的对象的任务的持续时间，冲洗和/或写入到磁盘的任务结束
cache=TRUE, cachePolicy="none", writeToDisk=TRUE: keep all objects in memory until removed with track.flush; write changed objects to disk immediately
缓存= TRUE，cachePolicy =“无”，writeToDisk = TRUE：保持内存中，直到立即track.flush，写更改的对象中删除磁盘中的所有对象
cache=TRUE, cachePolicy="none", writeToDisk=FALSE: keep all objects in memory until removed with track.flush; don't automatically write changed objects to disk (use track.save)
缓存= TRUE，cachePolicy =“无”，writeToDisk = FALSE：保持所有对象在内存中，直到删除track.flush;不会自动更改的对象写入到磁盘（使用track.save）
cache=FALSE, cachePolicy="none", writeToDisk=TRUE: keep no objects in memory; write changed objects to disk immediately
缓存= FALSE，cachePolicy =“无”，writeToDisk = TRUE：保持在内存中的任何对象，写立即改变对象到磁盘
Performance tuning is a possible area of future development of the track package, at as version 0.9-9, the defaults settings of cache=TRUE, cachePolicy="tltPurge", and writeToDisk=TRUE work well. However, smarter caching based on access patterns to objects is certainly possible.
性能优化是一个可能的领域，未来发展的轨道包，在0.9-9版，默认设置cache=TRUE，cachePolicy="tltPurge"和writeToDisk=TRUE正常工作。然而，更智能高速缓存根据访问模式的对象是有可能的。
参见----------See Also----------
Overview and design of the track package.
track包的概述和设计。
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-10-1 11:20:09
