From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel.Thibault@drdc-rddc.gc.ca (Thibault, Daniel) Date: Tue, 4 Feb 2014 18:59:02 +0000 Subject: [lttng-dev] Questions about JUL (was: Re: lttng-dev Digest, Vol 67, Issue 48) Message-ID: <48CF5AC71E61DB46B70D0F388054EFFD267DE218@VAL-E-02.valcartier.drdc-rddc.gc.ca> ---------------------------------------------------------------------- Date: Tue, 4 Feb 2014 12:17:36 -0500 From: David Goulet To: Jim Dumont Cc: "lttng-dev at lists.lttng.org" >> 3) add-context: does --jul have the same possible context types as --userspace (i.e. ip, pthread_id, procname, vpid, vtid)? > > Nope. What are the possible context types then? Or is it just that you can't apply a filter to a jul event? >> 4) enable-channel: >> 4.1) Are the --jul --subbuf-size, --num-subbuf and --read-timer defaults the same as with --userspace? > > Nope. JUL uses it's internal channel so basically enable channel does NOT support the jul domain thus not having -j in the help/man. So you turn jul events on and off using enable/disable-event --all instead? This is getting a tad confusing: jul events force you to use only enable/disable-event but kernel syscalls force you to use only enable/disable-channel... >> 4.4) If yes, won't they all degenerate to the virtual machine's user and process IDs? > > Not sure I understand this one? A Java application is interpreted and runs in a Java virtual machine (JVM). The userID and processID of any jul events are thus likely to be those of the JVM process. I would expect Java apps launched by separate users to launch separate JVM instances, but I would also expect two separate Java apps launched by the same user to share a single JVM (the user's) and, therefore, their process IDs. This could get fun with multi-threaded Java apps. > Now after answering all this, I feel like either creating a lttng-jul man page or adding a special section in "lttng.1" for the JUL domain explaining all this. Thoughts? We definitely need an additional section in "lttng.1". Daniel U. Thibault Protection des syst?mes et contremesures (PSC) | Systems Protection & Countermeasures (SPC) Cyber s?curit? pour les missions essentielles (CME) | Mission Critical Cyber Security (MCCS) R & D pour la d?fense Canada - Valcartier (RDDC Valcartier) | Defence R&D Canada - Valcartier (DRDC Valcartier) 2459 route de la Bravoure Qu?bec QC G3J 1X5 CANADA Vox : (418) 844-4000 x4245 Fax : (418) 844-4538 NAC : 918V QSDJ Gouvernement du Canada | Government of Canada