http://redwolf.cdf.toronto.edu:9999/csc309/servlet/HelloWorld - PDF document

http://redwolf.cdf.toronto.edu:9999/csc309/servlet/HelloWorldÐe.g.,http://localhost:9999/csc309/serlvet/HelloWorld¥Never hardcode machine names or port numbersin your applications -- use relative URLs instead!8Tomcat Directories¥bin: Includes startup and shutdown scripts¥conf: Configuration files including server.xml (on CDF,this is generated the first time you run bin/start.sh) andtomcat-users.xml¥logs: ServerÕs log files¥webapps: Applications¥work: ServerÕs temporary files. It is safe (and sometimeshelpful) to delete this directory after the server hasbeen shutdown9Other Issues about Tomcat¥Tomcat manager¥Debugging servlets¥Using Eclipse¥Installing Tomcat on your own computer¥Reference: AliÕs tutorial from the summer2008 term10Brief Preview of Scheduling¥Multiple threads ready to run¥Some mechanism for switching betweenthemÐContext switches¥Some policy for choosing the next threadto runÐThis policy may be pre-emptiveÐMeaning thread canÕt anticipate when it maybe forced to yield the CPUÐBy design, it is not easy to detect it hashappened (only the timing changes)11Synchronization¥Threads interact in a multiprogrammedsystemÐTo share resources (such as shared data)ÐTo coordinate their execution¥Arbitrary interleaving of thread executionscan have unexpected consequencesÐWe need a way to restrict the possibleinterleavings of executionsÐScheduling is invisible to the application¥Synchronization is the mechanism that givesus this control12Motivating Example¥Suppose we write functions to handlewithdrawals and deposits to bank account:Withdraw(acct, amt) { balance = get_balance(acct); balance = balance - amt; put_balance(acct,balance); return balance;}Deposit(acct, amt) { balance = get_balance(acct); balance = balance + amt; put_balance(acct,balance); return balance;}¥Now suppose you share this account withsomeone and the balance is $1000¥You each go to separate ATM machines - youwithdraw $100 and your S.O. deposits shar