ableegoldman commented on a change in pull request #301:
URL: https://github.com/apache/kafka-site/pull/301#discussion_r485154723



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File path: 26/streams/developer-guide/memory-mgmt.html
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@@ -202,7 +202,10 @@ <h2><a class="toc-backref" href="#id3">RocksDB</a><a 
class="headerlink" href="#r
        <span class="o">}</span>
     <span class="o">}</span>
       </div>
-        <sup id="fn1">1. INDEX_FILTER_BLOCK_RATIO can be used to set a 
fraction of the block cache to set aside for "high priority" (aka index and 
filter) blocks, preventing them from being evicted by data blocks. See the full 
signature of the <a class="reference external" 
href="https://github.com/facebook/rocksdb/blob/master/java/src/main/java/org/rocksdb/LRUCache.java#L72";>LRUCache
 constructor</a>. </sup>
+        <sup id="fn1">1. INDEX_FILTER_BLOCK_RATIO can be used to set a 
fraction of the block cache to set aside for "high priority" (aka index and 
filter) blocks, preventing them from being evicted by data blocks. See the full 
signature of the <a class="reference external" 
href="https://github.com/facebook/rocksdb/blob/master/java/src/main/java/org/rocksdb/LRUCache.java#L72";>LRUCache
 constructor</a>.
+          NOTE: the boolean parameter in the cache constructor lets you 
control whether the cache should enforce a strict memory limit by failing the 
read or iteration in the rare cases where it might go larger than its capacity. 
Due to a
+          <a class="reference external" 
href="https://github.com/facebook/rocksdb/issues/6247";>bug in RocksDB</a>, this 
option cannot be used
+          if the write buffer memory is also counted against the cache. If you 
set this to true, you should NOT pass the cache in to the 
<code>WriteBufferManager</code> and just control the write buffer and cache 
memory separately.</sup>

Review comment:
       Nope, this is correct. As far as I know this has always been the case in 
every RocksDB version we've depended on but didn't discover the bug until just 
recently. (I believe it actually is fixed in some newer versions, so we may be 
able to remove this again once we upgrade)




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