System freezes during large file transfers (#3): Some systems recover; certain Java routines may cause problems; more

Recently we've been covering system-wide freezes under Mac OS X 10.3.5 that appear to be directly linked to heavy network activity. The problem is most common when users are downloading files through a file sharing application like BitTorrent, but also occur during a number of other transfer types.

In some cases, Macs seemingly succumbed to a system-wide freeze due to this problem actually recover after a few minutes. MacFixIt reader Marty Snyder writes:

"The finder does respond, after about two to three minutes of seeming to be unresponsive; then we get the spinning beach-ball for another two or three minutes; then we get a notice that we have lost our connection to the server. The finder returns, at that point, to being functional, but we must then reconnect to the server."

Certain Java routines may cause problems Marc Marshall has done some limited testing on a few file sharing applications that use certain Java networking routines, and made some interesting discoveries:

"These freezes definitely occur under all versions of 10.3--they are NOT specific to 10.3.5--and are most frequently precipitated by Java programs (most commonly the BitTorrent client Azureus that was mentioned by Kiran) that use certain networking routines. They are almost certainly caused by some bug in either OS X's Java implementation or the lower-level networking implementation it interfaces with, and are far more common on dual-processor Macs--most people with single-processor Macs report no issues at all.

"I did some relatively thorough testing with Azureus on my G5 DP2.0, and have found that the versions since 2.0.8.4 (version 2.1.0.0 and above, that is; 2.1.0.4 is the current version) are much better at causing freezes (and occasional kernel panics) than earlier versions. 2.8.0.4 will cause a crash after roughly 2-5 days of use, regardless of the version of 10.3 or the version of Java installed (the latest Java update apparently does not help).

"Version 2.1.0.0 of Azureus will consistently crash my G5 within 15 minutes of starting it; reinstalling Java and changing settings does not help. Turning on the 'Slowly Connect New Peers' option seems to help to some degree, but does not resolve the issue.

Link to AirPort Some users are experiencing this problem only when connected through an AirPort interface, and not when using an Ethernet cable or other connection method.

Reader Alex writes "I experienced my first system freeze as described today while downloading a 266 MB file over AirPort. Cursor moved but nothing else - even the clock was not changing. Holding the power button allowed a re-start. I tried again - with the same results. I then ran an Ethernet cable from the hub to my Mac and tried the same file download with the computer's AirPort card turned off (the base station was still doing its job without a hitch during the system freezes). The file downloaded without problem."

Specific sites As previously reported, some readers only experience this problem when accessing specific web sites:

"I've been having problems that may be related to this issue. My experience is the following -- I will go to a certain web site (Overstock.com has been reproducible with this but there are others) and suddenly disk activity will go to 100%. This is checked by using MenuMeters and Activity Monitor. At this point even internet access is reported as down and Entourage is unable to get any connection for emails, even though it was connected just moments before and I am on a cable connection with another computer that is able to continue to access the internet without difficulty. At this point it is only a matter of time before the system finally freezes and needs to be restarted by using the Reset button. If I am lucky enough to quit programs and Log Out I am still unable to access the internet. Only a Restart will work to solve this issue."

If you are experiencing similar issues, or have any other feedback on this topic, please drop us a line at late-breakers@macfixit.com.

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