Performance problem (massive imap getUnreadMessageCount requests)

Question

Hello,
I'm working on a server that's supposed to access the unread message count of many IMAP users (up to 40/second).
I'm facing performance issues : i can't get more than ~20/second.
I tried using multiple stores (and sessions) but it won't go faster. The performance bottleneck seems to be in the "connect" part.
I can provide the server configuration files if needed.
Maybe there's performance tuning I'm not aware of that I could use, can you help?
A very basic program that gets called way too often :
import java.util.Date;
import java.util.Properties;
import javax.mail.Folder;
import javax.mail.Session;
import com.sun.mail.imap.IMAPStore;
public class MessagesDao {
* singleton
private static MessagesDao instance = null;
* singleton
* @return
public static synchronized MessagesDao getInstance() {
if (instance == null) {
instance = new MessagesDao();
return instance;
private Session sessionImap;
* MessagesDao
private MessagesDao() {
final String portServeurImap = "143";
final String adresseServeurImap = "my_server";
final String imapConnectionPoolSize = "10";
final String imapConnectionPoolTimeout = "10";
final String imapTimeout = "2000";
final String imapConnectionTimeout = "2000";
final Properties propSessionImap = new Properties();
propSessionImap.put("mail.store.protocol", "imap");
propSessionImap.put("mail.imap.connectionpoolsize", imapConnectionPoolSize);
propSessionImap.put("mail.imap.connectionpooltimeout", imapConnectionPoolTimeout);
propSessionImap.put("mail.imap.timeout", imapTimeout);
propSessionImap.put("mail.imap.connectiontimeout", imapConnectionTimeout);
propSessionImap.put("mail.imap.port", portServeurImap);
propSessionImap.put("mail.imap.host", adresseServeurImap);
propSessionImap.put("mail.imap.auth", "true");
propSessionImap.put("mail.imap.separatestoreconnection", "true");
propSessionImap.put("mail.imap.appendbuffersize", -1);
propSessionImap.put("mail.debug", "false");
this.sessionImap = Session.getInstance(propSessionImap);
* user : someName@myDomain
public int getUnreadMessageCount(String user){
IMAPStore store = null;
try {
long timeStart = new Date().getTime();
store = (IMAPStore) this.sessionImap.getStore();
long timeGetStore = new Date().getTime();
store.connect(user, "fakepass");
long timeConnect = new Date().getTime();
Folder inbox = store.getFolder("inbox");
int count = inbox.getUnreadMessageCount();
System.out.println("-----> unread " + user + " : " + count + "( getStore : " + (timeGetStore - timeStart) + ", connect : " + (timeConnect - timeGetStore)+")");
return count;
} catch (Exception e) {
e.printStackTrace();
return -1;
} finally {
try {
store.close();
} catch (Exception e) {
Edited by: user13568923 on 29 déc. 2010 09:46

Answer 1

A single user never opens more than 2 folders at a time. I guess I don't really need the 10 folder pool...
Here's what the traffic looks like :
"5388","16.536513","cli","serv","TCP","46434 > imap [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=58648306 TSER=0 WS=6"
"5389","16.537545","serv","cli","TCP","imap > 46434 [SYN, ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1460 TSV=3608644264 TSER=58648306 WS=7"
"5390","16.537567","cli","serv","TCP","46434 > imap [ACK] Seq=1 Ack=1 Win=5888 Len=0 TSV=58648306 TSER=3608644264"
"5391","16.539219","serv","cli","IMAP","Response: * OK Dovecot ready."
"5392","16.539251","cli","serv","TCP","46434 > imap [ACK] Seq=1 Ack=22 Win=5888 Len=0 TSV=58648307 TSER=3608644266"
"5394","16.540835","cli","serv","IMAP","Request: A0 CAPABILITY"
"5397","16.542140","serv","cli","TCP","imap > 46434 [ACK] Seq=22 Ack=16 Win=5888 Len=0 TSV=3608644269 TSER=58648307"
"5398","16.542399","serv","cli","IMAP","Response: * CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS QUOTA STARTTLS AUTH=PLAIN"
"5399","16.542733","cli","serv","IMAP","Request: A1 AUTHENTICATE PLAIN"
"5415","16.584176","serv","cli","TCP","imap > 46434 [ACK] Seq=202 Ack=39 Win=5888 Len=0 TSV=3608644310 TSER=58648307"
"5421","16.594994","serv","cli","IMAP","Response: + "
"5427","16.595570","cli","serv","IMAP","Request: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA etc=="
"5433","16.596586","serv","cli","TCP","imap > 46434 [ACK] Seq=206 Ack=129 Win=5888 Len=0 TSV=3608644322 TSER=58648321"
"6420","18.341472","serv","cli","IMAP","Response: A1 OK Logged in."
"6421","18.341639","cli","serv","IMAP","Request: A2 CAPABILITY"
"6437","18.370916","serv","cli","TCP","imap > 46434 [ACK] Seq=224 Ack=144 Win=5888 Len=0 TSV=3608646052 TSER=58648757"
"6526","18.602063","serv","cli","IMAP","Response: * CAPABILITY IMAP4rev1 SASL-IR SORT THREAD=REFERENCES MULTIAPPEND UNSELECT LITERAL+ IDLE CHILDREN NAMESPACE LOGIN-REFERRALS QUOTA"
"6528","18.604615","cli","serv","IMAP","Request: A3 LIST "" inbox"
"6542","18.642682","serv","cli","TCP","imap > 46434 [ACK] Seq=384 Ack=162 Win=5888 Len=0 TSV=3608646316 TSER=58648823"
"6555","18.668482","serv","cli","IMAP","Response: * LIST (\HasNoChildren) "." "INBOX""
"6557","18.668945","cli","serv","IMAP","Request: A4 STATUS INBOX (MESSAGES RECENT UNSEEN UIDNEXT UIDVALIDITY)"
"6578","18.712320","serv","cli","IMAP","Response: * STATUS "INBOX" (MESSAGES 1 RECENT 0 UIDNEXT 10 UIDVALIDITY 1271690632 UNSEEN 1)"
"6584","18.713558","cli","serv","IMAP","Request: A5 LOGOUT"
"6588","18.728700","serv","cli","IMAP","Response: * BYE Logging out"
"6589","18.728774","serv","cli","IMAP","Response: A5 OK Logout completed."
"6590","18.728914","cli","serv","TCP","46434 > imap [ACK] Seq=235 Ack=597 Win=8000 Len=0 TSV=58648854 TSER=3608646398"
"6591","18.729118","cli","serv","TCP","46434 > imap [FIN, ACK] Seq=235 Ack=597 Win=8000 Len=0 TSV=58648854 TSER=3608646398"
It seems to me that the problem is server-side, in the login part.
Edited by: user13568923 on 18 janv. 2011 00:41