java - Tomcat Configuration using DBCP -

-

we getting communicationsexception (from dbcp) after iding while (a few hours). error message (in exception) @ end of question - dont see wait_timeout defined in of configuration files. (where should look? somewhere out of tomcat/conf directory?).

secondly, suggested exception, 1 put "connector/j connection property 'autoreconnect=true'"? here resource definition in file conf/context.xml in tomcat set up:

<resource name="jdbc/tomcatresourcename" auth="container" type="javax.sql.datasource"            maxactive="100" maxidle="30" maxwait="10000"            removeabandoned="true" removeabandonedtimeout="60" logabandoned="true"            username="xxxx" password="yyyy"            driverclassname="com.mysql.jdbc.driver"            url="jdbc:mysql://127.0.0.1:3306/dbname?autoreconnect=true"/>

thirdly, why jvm wait till call executequery() throw exception? if connection has timed out, getconnection method should throw exception, shouldn't it? section of source code talking about:

        try {                 conn = getconnection (true);                 stmt = conn.createstatement (resultset.type_scroll_insensitive,                                                 resultset.concur_read_only);                 rset = stmt.executequery (bquery);                 while (rset.next()) {                      ....

finally, here 1st few lines of stack trace...

com.mysql.jdbc.exceptions.jdbc4.communicationsexception: last packet received server 84,160,724 milliseconds ago.  last packet sent server 84,160,848 milliseconds ago. longer server configured value of 'wait_timeout'. should consider either expiring and/or testing connection validity before use in application, increasing server configured values client timeouts, or using connector/j connection property 'autoreconnect=true' avoid problem. @ sun.reflect.nativeconstructoraccessorimpl.newinstance0(native method) @ sun.reflect.nativeconstructoraccessorimpl.newinstance(nativeconstructoraccessorimpl.java:57) @ sun.reflect.delegatingconstructoraccessorimpl.newinstance(delegatingconstructoraccessorimpl.java:45) @ java.lang.reflect.constructor.newinstance(constructor.java:532) @ com.mysql.jdbc.util.handlenewinstance(util.java:406) @ com.mysql.jdbc.sqlerror.createcommunicationsexception(sqlerror.java:1074) @ com.mysql.jdbc.mysqlio.send(mysqlio.java:3291) @ com.mysql.jdbc.mysqlio.sendcommand(mysqlio.java:1938) @ com.mysql.jdbc.mysqlio.sqlquerydirect(mysqlio.java:2107) @ com.mysql.jdbc.connectionimpl.execsql(connectionimpl.java:2642) @ com.mysql.jdbc.connectionimpl.execsql(connectionimpl.java:2571) @ com.mysql.jdbc.statementimpl.executequery(statementimpl.java:1451) @ org.apache.tomcat.dbcp.dbcp.delegatingstatement.executequery(delegatingstatement.java:208)

these reasons of thinking "forget dbcp, may dependent on ide configurations , under-the-hood magic drivermanager.getconnection(...) may more reliable". comments on that? thank insights, - ms

since dbcp keeps returned mysql connections open upcoming connection requests, fall victims mysql server timeout.

dbcp has number of features can (can used starting tomcat 5.5 iirc).

validationquery="select 1" testonborrow="true"

the validation makes sure connection valid before returning webapp executing 'borrow' method. flag of course, enables feature.

if timeout (8 hours believe) elapsed , connection dead, new connection tested (if there none anymore, created) , provided webapp.

other possible approaches:

  1. use testwhileidle="true" dbcp in resource settings check idle connections before effective request detected.

  2. use 'connectionproperties' harden mysql connection (e.g. autoreconnect/autoreconnectforpools=true)


Comments

Post a Comment

Popular posts from this blog

python - Scipy curvefit RuntimeError:Optimal parameters not found: Number of calls to function has reached maxfev = 1000 -

-
Image
i want make logharitmic fit. keep getting runtime error: optimal parameters not found: number of calls function has reached maxfev = 1000 i use following script. can tell me go wrong? use spyder still beginner. import math import matplotlib mpl scipy.optimize import curve_fit import numpy np #data f1=[735.0,696.0,690.0,683.0,680.0,678.0,679.0,675.0,671.0,669.0,668.0,664.0,664.0] t1=[1,90000.0,178200.0,421200.0,505800.0,592200.0,768600.0,1036800.0,1371600.0,1630800.0,1715400.0,2345400.0,2409012.0] f1n=np.array(f1) t1n=np.array(t1) plt.plot(t1,f1,'ro',label="original data") # curvefit def func(t,a,b): return a+b*np.log(t) t=np.linspace(0,3600*24*28,13) popt, pcov = curve_fit(func, t, f1n, maxfev=1000) plt.plot(t, func(t, *popt), label="fitted curve") plt.legend(loc='upper left') plt.show() your original data t1 , f1 . therefore curve_fit should given t1 second argument, not t . popt, pcov = curve_fit(func,
Read more

c# - How to add a new treeview at the selected node? -

-
i have treeview 4 levels; parent, child, grandchild, great-grandchild. selectednode @ grandchild level. what i'm trying create new "treeview" @ grandchild - no, dont wnat create new node "selectednode" (grandchild). should somelike this: parent child grandchild (new treeview) parent grandchild great-grandchild child great-grandchild child grandchild grandchild it similar parent table mother , father went off , had new childern different spouse other spouse of there existing children. private sub populaterootlevel() ' query find first round of parent populatenodes(dt, jcatreeview.nodes) end sub private sub populatenodes(byval dt datatable, byval nodes treenodecollection) each dr datarow in dt.rows dim tn new treenode() tn.text = dr("title").tostring()
Read more

java - netbeans "Please wait - classpath scanning in progress..." -

-
when try compile netbeans projects message/error : "please wait - classpath scanning in progress..." and nothing happens , have have wait enternity conmpile "hello world"... now first thing have moved new office building, laptop same. it's secure enviroment lot of "security", can't connect anywhere almost. have changed user dir in netbeans.conf save data in c:\program files\user any ideas how fix this? alrady tried reinstalling netbeans, changing save location between standart , newone... just ideas find problem look @ cpu - netbeans busy (100% on 1 core) or blocking (95% idle)? standard, ant or maven build? libraries , use absolute or relative paths? start simple "hello world" project (no dependencies), add 1 lib (log4j or similiar), located in project folder , - if works - move lib other locations (choose locations similiar libs on real classpath) there chance, don't have access rights folders/shares conta
Read more