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https://issues.apache.org/jira/browse/CASSANDRA-4479?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13427012#comment-13427012
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Eric Dong commented on CASSANDRA-4479:
--------------------------------------
A quick-and-dirty laundry list of MBean setters:
{noformat}
$ find . -name '*MBean.java' -exec grep 'void set' {} +
./src/java/org/apache/cassandra/concurrent/JMXConfigurableThreadPoolExecutorMBean.java:
void setCorePoolSize(int n);
./src/java/org/apache/cassandra/db/ColumnFamilyStoreMBean.java: public void
setMinimumCompactionThreshold(int threshold);
./src/java/org/apache/cassandra/db/ColumnFamilyStoreMBean.java: public void
setMaximumCompactionThreshold(int threshold);
./src/java/org/apache/cassandra/db/ColumnFamilyStoreMBean.java: public void
setCompactionStrategyClass(String className) throws ConfigurationException;
./src/java/org/apache/cassandra/db/ColumnFamilyStoreMBean.java: public void
setCompressionParameters(Map<String,String> opts) throws ConfigurationException;
./src/java/org/apache/cassandra/gms/FailureDetectorMBean.java: public void
setPhiConvictThreshold(int phi);
./src/java/org/apache/cassandra/service/CacheServiceMBean.java: public void
setRowCacheSavePeriodInSeconds(int rcspis);
./src/java/org/apache/cassandra/service/CacheServiceMBean.java: public void
setKeyCacheSavePeriodInSeconds(int kcspis);
./src/java/org/apache/cassandra/service/CacheServiceMBean.java: public void
setRowCacheCapacityInMB(long capacity);
./src/java/org/apache/cassandra/service/CacheServiceMBean.java: public void
setKeyCacheCapacityInMB(long capacity);
./src/java/org/apache/cassandra/service/StorageProxyMBean.java: public void
setHintedHandoffEnabled(boolean b);
./src/java/org/apache/cassandra/service/StorageProxyMBean.java: public void
setMaxHintWindow(int ms);
./src/java/org/apache/cassandra/service/StorageProxyMBean.java: public void
setMaxHintsInProgress(int qs);
./src/java/org/apache/cassandra/service/StorageProxyMBean.java: public void
setRpcTimeout(Long timeoutInMillis);
./src/java/org/apache/cassandra/service/StorageServiceMBean.java: public
void setLog4jLevel(String classQualifier, String level);
./src/java/org/apache/cassandra/service/StorageServiceMBean.java: public
void setStreamThroughputMbPerSec(int value);
./src/java/org/apache/cassandra/service/StorageServiceMBean.java: public
void setCompactionThroughputMbPerSec(int value);
./src/java/org/apache/cassandra/service/StorageServiceMBean.java: public
void setIncrementalBackupsEnabled(boolean value);
{noformat}
DatabaseDescriptor setters; according to
[ArchitectureInternals|http://wiki.apache.org/cassandra/ArchitectureInternals],
all node configuration parameters should be in here:
{noformat}
$ grep 'void set' src/java/org/apache/cassandra/config/DatabaseDescriptor.java
public static void setPartitioner(IPartitioner newPartitioner)
public static void setEndpointSnitch(IEndpointSnitch eps)
public static void setRpcTimeout(Long timeOutInMillis)
public static void setInMemoryCompactionLimit(int sizeInMB)
public static void setCompactionThroughputMbPerSec(int value)
public static void setStreamThroughputOutboundMegabitsPerSec(int value)
public static void setBroadcastAddress(InetAddress broadcastAdd)
public static void setDynamicUpdateInterval(Integer dynamicUpdateInterval)
public static void setDynamicResetInterval(Integer dynamicResetInterval)
public static void setDynamicBadnessThreshold(Double
dynamicBadnessThreshold)
public static void setIncrementalBackupsEnabled(boolean value)
{noformat}
> JMX attribute setters not consistent with cassandra.yaml
> --------------------------------------------------------
>
> Key: CASSANDRA-4479
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4479
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 1.1.2
> Reporter: Eric Dong
>
> If a setting is configurable both via cassandra.yaml and JMX, the two should
> be consistent. If that doesn't hold, then the JMX setter can't be trusted.
> Here I present the example of phi_convict_threshold.
> I'm trying to set phi_convict_threshold via JMX, which sets
> FailureDetector.phiConvictThreshold_, but this doesn't update
> Config.phi_convict_threshold, which gets its value from cassandra.yaml when
> starting up.
> Some places, such as FailureDetector.interpret(InetAddress), use
> FailureDetector.phiConvictThreshold_; others, such as AntiEntropyService.line
> 813 in cassandra-1.1.2, use Config.phi_convict_threshold:
> {code}
> // We want a higher confidence in the failure detection than
> usual because failing a repair wrongly has a high cost.
> if (phi < 2 * DatabaseDescriptor.getPhiConvictThreshold())
> return;
> {code}
> where DatabaseDescriptor.getPhiConvictThreshold() returns
> Conf.phi_convict_threshold.
> So, it looks like there are cases where a value is stored in multiple places,
> and setting the value via JMX doesn't set all of them. I'd say there should
> only be a single place where a configuration parameter is stored, and that
> single field:
> * should read in the value from cassandra.yaml, optionally falling back to a
> sane default
> * should be the field that the JMX attribute reads and sets, and
> * any place that needs the current global setting should get it from that
> field. However, there could be cases where you read in a global value at the
> start of a task and keep that value locally until the end of the task.
> Also, anything settable via JMX should be volatile or set via a synchronized
> setter, or else according to the Java memory model other threads may be stuck
> with the old setting.
> So, I'm requesting the following:
> * Setting up guidelines for how to expose a configuration parameter both via
> cassandra.yaml and JMX, based on what I've mentioned above
> * Going through the list of configuration parameters and fixing any that
> don't match those guidelines
> I'd also recommend logging any changes to configuration parameters.
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