Redmine

there is the issue's log，if log is not enough,please let me method to debug it,thank you

ThreadError (can't create Thread: Resource temporarily unavailable):
app/models/mailer.rb:458:in `deliver_mail'
config/initializers/10-patches.rb:154:in `deliver'
app/models/mailer.rb:98:in `block (2 levels) in deliver_issue_edit'
app/models/issue.rb:952:in `each_notification'
app/models/mailer.rb:97:in `block in deliver_issue_edit'
app/models/journal.rb:90:in `block in each_notification'
app/models/journal.rb:88:in `each'
app/models/journal.rb:88:in `each_notification'
app/models/mailer.rb:96:in `deliver_issue_edit'
app/models/journal.rb:302:in `send_notification'
app/models/journal.rb:67:in `save'
app/models/issue.rb:1681:in `create_journal'
app/models/issue.rb:182:in `create_or_update'
app/controllers/issues_controller.rb:499:in `block in save_issue_with_child_records'
app/controllers/issues_controller.rb:487:in `save_issue_with_child_records'
app/controllers/issues_controller.rb:185:in `update'
lib/redmine/sudo_mode.rb:63:in `sudo_mode'