java - Locked object found on oracle.jdbc.driver.T4CConnection -


i using jmc perform application profiling , did not see locked/thread contention shown in screenshot below.

enter image description here enter image description here enter image description here ran sql below (every few secs) did not return result.

select     (select username v$session sid=a.sid) blocker,    a.sid,    ' blocking ',    (select username v$session sid=b.sid) blockee,    b.sid     v$lock a,     v$lock b     a.block = 1 ,     b.request > 0 ,     a.id1 = b.id1 ,     a.id2 = b.id2;

what caused of lock database connection? database record/table locks?

below thread dump have extracted during execution of program when seems running forever.

   java.lang.thread.state: runnable     @ java.net.socketinputstream.socketread0(native method)     @ java.net.socketinputstream.socketread(socketinputstream.java:116)     @ java.net.socketinputstream.read(socketinputstream.java:170)     @ java.net.socketinputstream.read(socketinputstream.java:141)     @ oracle.net.ns.packet.receive(packet.java:283)     @ oracle.net.ns.datapacket.receive(datapacket.java:103)     @ oracle.net.ns.netinputstream.getnextpacket(netinputstream.java:230)     @ oracle.net.ns.netinputstream.read(netinputstream.java:175)     @ oracle.net.ns.netinputstream.read(netinputstream.java:100)     @ oracle.net.ns.netinputstream.read(netinputstream.java:85)     @ oracle.jdbc.driver.t4csocketinputstreamwrapper.readnextpacket(t4csocketinputstreamwrapper.java:123)     @ oracle.jdbc.driver.t4csocketinputstreamwrapper.read(t4csocketinputstreamwrapper.java:79)     @ oracle.jdbc.driver.t4cmarengine.unmarshalub1(t4cmarengine.java:1122)     @ oracle.jdbc.driver.t4cmarengine.unmarshalsb1(t4cmarengine.java:1099)     @ oracle.jdbc.driver.t4cttifun.receive(t4cttifun.java:288)     @ oracle.jdbc.driver.t4cttifun.dorpc(t4cttifun.java:191)     @ oracle.jdbc.driver.t4c8oall.dooall(t4c8oall.java:523)     @ oracle.jdbc.driver.t4cpreparedstatement.dooall8(t4cpreparedstatement.java:207)     @ oracle.jdbc.driver.t4cpreparedstatement.executefordescribe(t4cpreparedstatement.java:863)     @ oracle.jdbc.driver.oraclestatement.executemaybedescribe(oraclestatement.java:1153)     @ oracle.jdbc.driver.oraclestatement.doexecutewithtimeout(oraclestatement.java:1275)     @ oracle.jdbc.driver.oraclepreparedstatement.executeinternal(oraclepreparedstatement.java:3576)     @ oracle.jdbc.driver.oraclepreparedstatement.executequery(oraclepreparedstatement.java:3620)     - locked <0x00000007af3423c0> (a oracle.jdbc.driver.t4cconnection)

you're confusing database locks java locks here. jmc shows locks inside java program (synchronized blocks, waits etc), knows nothing what's going on inside db. sql-query shows locks on db level (table locks, row locks etc) , knows nothing locks inside java program. absolutely different areas , absolutely different locks.

what have here dump of thread holds lock on object of type t4cconnection address 0x7af3423c0. means thread in process of executing code inside synchronized(connection) block. that's all. thread not blocked other threads (otherwise state wouldn't runnable, waiting or blocked). it's running , reading network socket (probably, response db).

such behaviour absolutely normal. db driver synchronization on connection instance while it's in process of executing sql-query not allow other threads use in parallel.

there's nothing should worry on screenshot , in thread dump.


-

Comments

Post a Comment

Popular posts from this blog

amazon web services - S3 Pre-signed POST validate file type? -

i know it's possible put limit on file size content-length-range header. possible validate file type? https://docs.aws.amazon.com/amazons3/latest/dev/httppostforms.html#policyconditions i see there content-type header, if set say, audio/mp3 allow mp3 files , return error if file not mp3? i found previous question answers mention validating file size: s3 direct upload restricting file size , type you can specify content-type @ post request. you can specify @ signature, post must done content-type: { "expiration": "2007-12-01t12:00:00.000z", "conditions": [ {"acl": "public-read" }, {"bucket": "johnsmith" }, {"content-type: "audio/mp3"} ] } creating html form (using aws signature version 4) edit: @ previous question found, checking content-type.
Read more

c# - Check Keyboard Input Winforms -

i wondering if instead of doing this protected override void onkeydown(keyeventargs e) { if (e.keycode == keys.a) console.writeline("the key down."); } i set bool method , this: if(keydown(keys.a)) // whatever here i've been sitting here ages trying figure out how it. can't wrap head around it. in case wondering, plan call bool inside different method, check input. since want perform action after pressing key, using keydown event enough. but in cases suppose want check if specific key down in middle of process, can use getkeystate method way: [dllimport("user32.dll", charset = charset.auto, exactspelling = true)] public static extern short getkeystate(int keycode); public const int key_pressed = 0x8000; public static bool iskeydown(keys key) { return convert.toboolean(getkeystate((int)key) & key_pressed); } you should know, each time check key state using example iskeydown(keys.a) method returns true if ke...
Read more