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https://issues.apache.org/jira/browse/HBASE-12393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14275816#comment-14275816
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Nick Dimiduk commented on HBASE-12393:
--------------------------------------
hi [~chia7712]. We have a test called TestRSStatusServlet. I think it makes
sense to add a test there. You should be able to use Mockito or reflection to
force CacheConfig.getBlockCache() to return null. Mind taking a stab at adding
such a test? While you're at it, you can add the LOG.warn statements JM
mentioned above. I've assigned the ticket to you.
FYI, we always apply patches first for master and then back them to the various
release branches. So in this case, a fix will be needed for master, branch-1,
branch-1.0, and 0.98. Let us know if you have troubles, I/we are happy to help.
> The regionserver web will throw exception if we disable block cache
> -------------------------------------------------------------------
>
> Key: HBASE-12393
> URL: https://issues.apache.org/jira/browse/HBASE-12393
> Project: HBase
> Issue Type: Bug
> Components: regionserver, UI
> Affects Versions: 0.98.7
> Environment: ubuntu 12.04 64bits, hadoop-2.2.0, hbase-0.98.7-hadoop2
> Reporter: ChiaPing Tsai
> Assignee: ChiaPing Tsai
> Priority: Minor
> Fix For: 1.0.0, 2.0.0, 0.98.10, 1.1.0
>
> Attachments: HBASE-12393.patch
>
>
> The CacheConfig.getBlockCache() will return the null point when we set
> hfile.block.cache.size to zero.
> The BlockCacheTmpl.jamon doesn't make a check on null blockcache.
> {code}
> <%if cacheConfig == null %>
> <p>CacheConfig is null</p>
> <%else>
> <table class="table table-striped">
> <tr>
> <th>Attribute</th>
> <th>Value</th>
> <th>Description</th>
> </tr>
> <tr>
> <td>Size</td>
> <td><%
> StringUtils.humanReadableInt(cacheConfig.getBlockCache().size()) %></td>
> <td>Total size of Block Cache (bytes)</td>
> </tr>
> <tr>
> <td>Free</td>
> <td><%
> StringUtils.humanReadableInt(cacheConfig.getBlockCache().getFreeSize())
> %></td>
> <td>Free space in Block Cache (bytes)</td>
> </tr>
> <tr>
> <td>Count</td>
> <td><% String.format("%,d",
> cacheConfig.getBlockCache().getBlockCount()) %></td>
> <td>Number of blocks in Block Cache</td>
> </tr>
> <tr>
> <td>Evicted</td>
> <td><% String.format("%,d",
> cacheConfig.getBlockCache().getStats().getEvictedCount()) %></td>
> <td>Number of blocks evicted</td>
> </tr>
> <tr>
> <td>Evictions</td>
> <td><% String.format("%,d",
> cacheConfig.getBlockCache().getStats().getEvictionCount()) %></td>
> <td>Number of times an eviction occurred</td>
> </tr>
> <tr>
> <td>Hits</td>
> <td><% String.format("%,d",
> cacheConfig.getBlockCache().getStats().getHitCount()) %></td>
> <td>Number requests that were cache hits</td>
> </tr>
> <tr>
> <td>Hits Caching</td>
> <td><% String.format("%,d",
> cacheConfig.getBlockCache().getStats().getHitCachingCount()) %></td>
> <td>Cache hit block requests but only requests set to use Block
> Cache</td>
> </tr>
> <tr>
> <td>Misses</td>
> <td><% String.format("%,d",
> cacheConfig.getBlockCache().getStats().getMissCount()) %></td>
> <td>Number of requests that were cache misses</td>
> </tr>
> <tr>
> <td>Misses Caching</td>
> <td><% String.format("%,d",
> cacheConfig.getBlockCache().getStats().getMissCount()) %></td>
> <td>Block requests that were cache misses but only requests set to
> use Block Cache</td>
> </tr>
> <tr>
> <td>Hit Ratio</td>
> <td><% String.format("%,.2f",
> cacheConfig.getBlockCache().getStats().getHitRatio() * 100) %><% "%" %></td>
> <td>Hit Count divided by total requests count</td>
> </tr>
> {code}
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