[jira] [Updated] (CASSANDRA-2597) inconsistent implementation of 'cumulative distribution function' for Exponential Distribution
[
https://issues.apache.org/jira/browse/CASSANDRA-2597?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Brandon Williams updated CASSANDRA-2597:
Fix Version/s: (was: 0.7.7)
0.8.1
inconsistent implementation of 'cumulative distribution function' for
Exponential Distribution
--
Key: CASSANDRA-2597
URL: https://issues.apache.org/jira/browse/CASSANDRA-2597
Project: Cassandra
Issue Type: Bug
Components: Core
Reporter: Jonathan Ellis
Assignee: paul cannon
Priority: Minor
Fix For: 0.8.1
Attachments: 0001-simplify-failure-detection-calculations.txt
As reported on the mailing list
(http://mail-archives.apache.org/mod_mbox/cassandra-dev/201104.mbox/%3CAANLkTimdMSLE8-z0x+0kvzqp7za3AEMLaOFXvd4Z=t...@mail.gmail.com%3E),
{quote}
I just found there are two implementations of 'cumulative distribution
function' for Exponential Distribution and there are inconsistent :
*FailureDetector*
{code:java}
org.apache.cassandra.gms.ArrivalWindow.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1)*(t)/mean;
return *Math.pow(Math.E, exponent)*;
}
{code}
*DynamicEndpointSnitch*
{code:java}
org.apache.cassandra.locator.AdaptiveLatencyTracker.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1) * (t) / mean;
return *1 - Math.pow( Math.E, exponent);*
}
{code}
According to the Exponential Distribution cumulative distribution function
definitionhttp://en.wikipedia.org/wiki/Exponential_distribution#Cumulative_distribution_function,
the later one is correct
{quote}
... however FailureDetector has been working as advertised for some time now.
Does this mean the Snitch version is actually wrong?
--
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For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Updated] (CASSANDRA-2597) inconsistent implementation of 'cumulative distribution function' for Exponential Distribution
[
https://issues.apache.org/jira/browse/CASSANDRA-2597?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
paul cannon updated CASSANDRA-2597:
---
Attachment: 0001-simplify-failure-detection-calculations.txt
No changes to the tests were necessary.
inconsistent implementation of 'cumulative distribution function' for
Exponential Distribution
--
Key: CASSANDRA-2597
URL: https://issues.apache.org/jira/browse/CASSANDRA-2597
Project: Cassandra
Issue Type: Bug
Components: Core
Reporter: Jonathan Ellis
Assignee: paul cannon
Priority: Minor
Fix For: 0.7.7
Attachments: 0001-simplify-failure-detection-calculations.txt
As reported on the mailing list
(http://mail-archives.apache.org/mod_mbox/cassandra-dev/201104.mbox/%3CAANLkTimdMSLE8-z0x+0kvzqp7za3AEMLaOFXvd4Z=t...@mail.gmail.com%3E),
{quote}
I just found there are two implementations of 'cumulative distribution
function' for Exponential Distribution and there are inconsistent :
*FailureDetector*
{code:java}
org.apache.cassandra.gms.ArrivalWindow.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1)*(t)/mean;
return *Math.pow(Math.E, exponent)*;
}
{code}
*DynamicEndpointSnitch*
{code:java}
org.apache.cassandra.locator.AdaptiveLatencyTracker.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1) * (t) / mean;
return *1 - Math.pow( Math.E, exponent);*
}
{code}
According to the Exponential Distribution cumulative distribution function
definitionhttp://en.wikipedia.org/wiki/Exponential_distribution#Cumulative_distribution_function,
the later one is correct
{quote}
... however FailureDetector has been working as advertised for some time now.
Does this mean the Snitch version is actually wrong?
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Updated] (CASSANDRA-2597) inconsistent implementation of 'cumulative distribution function' for Exponential Distribution
[
https://issues.apache.org/jira/browse/CASSANDRA-2597?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ryan King updated CASSANDRA-2597:
-
Component/s: (was: Core)
Contrib
Description:
As reported on the mailing list
(http://mail-archives.apache.org/mod_mbox/cassandra-dev/201104.mbox/%3CAANLkTimdMSLE8-z0x+0kvzqp7za3AEMLaOFXvd4Z=t...@mail.gmail.com%3E),
{quote}
I just found there are two implementations of 'cumulative distribution
function' for Exponential Distribution and there are inconsistent :
*FailureDetector*
{code:java}
org.apache.cassandra.gms.ArrivalWindow.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1)*(t)/mean;
return *Math.pow(Math.E, exponent)*;
}
{code}
*DynamicEndpointSnitch*
{code:java}
org.apache.cassandra.locator.AdaptiveLatencyTracker.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1) * (t) / mean;
return *1 - Math.pow( Math.E, exponent);*
}
{code}
According to the Exponential Distribution cumulative distribution function
definitionhttp://en.wikipedia.org/wiki/Exponential_distribution#Cumulative_distribution_function,
the later one is correct
{quote}
... however FailureDetector has been working as advertised for some time now.
Does this mean the Snitch version is actually wrong?
was:
As reported on the mailing list
(http://mail-archives.apache.org/mod_mbox/cassandra-dev/201104.mbox/%3CAANLkTimdMSLE8-z0x+0kvzqp7za3AEMLaOFXvd4Z=t...@mail.gmail.com%3E),
{quote}
I just found there are two implementations of 'cumulative distribution
function' for Exponential Distribution and there are inconsistent :
*FailureDetector*
org.apache.cassandra.gms.ArrivalWindow.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1)*(t)/mean;
return *Math.pow(Math.E, exponent)*;
}
*DynamicEndpointSnitch*
org.apache.cassandra.locator.AdaptiveLatencyTracker.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1) * (t) / mean;
return *1 - Math.pow( Math.E, exponent);*
}
According to the Exponential Distribution cumulative distribution function
definitionhttp://en.wikipedia.org/wiki/Exponential_distribution#Cumulative_distribution_function,
the later one is correct
{quote}
... however FailureDetector has been working as advertised for some time now.
Does this mean the Snitch version is actually wrong?
Fix Version/s: (was: 0.7.7)
0.7.6
inconsistent implementation of 'cumulative distribution function' for
Exponential Distribution
--
Key: CASSANDRA-2597
URL: https://issues.apache.org/jira/browse/CASSANDRA-2597
Project: Cassandra
Issue Type: Bug
Components: Contrib
Reporter: Jonathan Ellis
Assignee: paul cannon
Priority: Minor
Fix For: 0.7.6
As reported on the mailing list
(http://mail-archives.apache.org/mod_mbox/cassandra-dev/201104.mbox/%3CAANLkTimdMSLE8-z0x+0kvzqp7za3AEMLaOFXvd4Z=t...@mail.gmail.com%3E),
{quote}
I just found there are two implementations of 'cumulative distribution
function' for Exponential Distribution and there are inconsistent :
*FailureDetector*
{code:java}
org.apache.cassandra.gms.ArrivalWindow.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1)*(t)/mean;
return *Math.pow(Math.E, exponent)*;
}
{code}
*DynamicEndpointSnitch*
{code:java}
org.apache.cassandra.locator.AdaptiveLatencyTracker.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1) * (t) / mean;
return *1 - Math.pow( Math.E, exponent);*
}
{code}
According to the Exponential Distribution cumulative distribution function
definitionhttp://en.wikipedia.org/wiki/Exponential_distribution#Cumulative_distribution_function,
the later one is correct
{quote}
... however FailureDetector has been working as advertised for some time now.
Does this mean the Snitch version is actually wrong?
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Updated] (CASSANDRA-2597) inconsistent implementation of 'cumulative distribution function' for Exponential Distribution
[
https://issues.apache.org/jira/browse/CASSANDRA-2597?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jonathan Ellis updated CASSANDRA-2597:
--
Component/s: (was: Contrib)
Core
Fix Version/s: (was: 0.7.6)
0.7.7
inconsistent implementation of 'cumulative distribution function' for
Exponential Distribution
--
Key: CASSANDRA-2597
URL: https://issues.apache.org/jira/browse/CASSANDRA-2597
Project: Cassandra
Issue Type: Bug
Components: Core
Reporter: Jonathan Ellis
Assignee: paul cannon
Priority: Minor
Fix For: 0.7.7
As reported on the mailing list
(http://mail-archives.apache.org/mod_mbox/cassandra-dev/201104.mbox/%3CAANLkTimdMSLE8-z0x+0kvzqp7za3AEMLaOFXvd4Z=t...@mail.gmail.com%3E),
{quote}
I just found there are two implementations of 'cumulative distribution
function' for Exponential Distribution and there are inconsistent :
*FailureDetector*
{code:java}
org.apache.cassandra.gms.ArrivalWindow.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1)*(t)/mean;
return *Math.pow(Math.E, exponent)*;
}
{code}
*DynamicEndpointSnitch*
{code:java}
org.apache.cassandra.locator.AdaptiveLatencyTracker.p(double)
double p(double t)
{
double mean = mean();
double exponent = (-1) * (t) / mean;
return *1 - Math.pow( Math.E, exponent);*
}
{code}
According to the Exponential Distribution cumulative distribution function
definitionhttp://en.wikipedia.org/wiki/Exponential_distribution#Cumulative_distribution_function,
the later one is correct
{quote}
... however FailureDetector has been working as advertised for some time now.
Does this mean the Snitch version is actually wrong?
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
