How do I get ruby to print a full backtrace instead of a truncated one

Question

When I get exceptions  it is often from deep within the call stack   When this happens  more often than not  the actual offending line of code is hidden from me   tmp rb 7 in  t   undefined method  bar  for nil NilClass  NoMethodError          from tmp rb 10 in  s          from tmp rb 13 in  r          from tmp rb 16 in  q          from tmp rb 19 in  p          from tmp rb 22 in  o          from tmp rb 25 in  n          from tmp rb 28 in  m          from tmp rb 31 in  l               8 levels            from tmp rb 58 in  c          from tmp rb 61 in  b          from tmp rb 64 in  a          from tmp rb 67   That      8 levels     truncation is causing me a great deal of trouble   I m not having much success googling for this one   How do I tell ruby that I want dumps to include the full stack

User · Answer

This mimics the official Ruby trace  if that s important to you   begin   0 0    or some other nonsense rescue   gt  e   puts e backtrace join   n t           sub   n t        e   e class        e class          n t   end   Amusingly  it doesn t handle  unhandled exception  properly  reporting it as  RuntimeError   but the location is correct

User · Answer

Exception backtrace has the entire stack in it   def do division by zero  5   0  end begin   do division by zero rescue   gt  exception   puts exception backtrace   raise   always reraise end    Inspired by Peter Cooper s Ruby Inside blog

User · Answer

IRB has a setting for this awful  feature   which you can customize   Create a file called    irbrc that includes the following line   IRB conf  BACK TRACE LIMIT    100   This will allow you to see 100 stack frames in irb  at least  I haven t been able to find an equivalent setting for the non-interactive runtime   Detailed information about IRB customization can be found in the Pickaxe book

User · Answer

You could also do this if you d like a simple one-liner   puts caller

User · Answer

This produces the error description and nice clean  indented stacktrace   begin                   Some exception throwing code rescue   gt  e   puts  Error during processing           puts  Backtrace  n t  e backtrace join   n t     end

User · Answer

You can also use backtrace Ruby gem  I m the author    require  backtrace  begin     do something dangerous rescue StandardError   gt  e   puts Backtrace new e  end

User · Answer

examine all threads backtraces to find the culprit  Even fully expanded call stack can still hide the actual offending line of code from you when you use more than one thread   Example  One thread is iterating ruby Hash  other thread is trying to modify it  BOOM  Exception  And the problem with the stack trace you get while trying to modify  busy  hash is that it shows you chain of functions down to the place where you re trying to modify hash  but it does NOT show who s currently iterating it in parallel  who owns it   Here s the way to figure that out by printing stack trace for ALL currently running threads  Here s how you do this     This solution was found in comment by  thedarkone on https   github com rails rails issues 24627 rescue Object   gt  boom      thread count   0     Thread list each do  t        thread count    1       err msg     --- thread   thread count  of total   Thread list size    t object id  backtrace begin  n          Lets see if we are able to pin down the culprit         by collecting backtrace for all existing threads        err msg    t backtrace join   n         err msg      n---thread   thread count  of total   Thread list size    t object id  backtrace end  n      end        and just print it somewhere you like       stderr puts err msg       raise   always reraise end   The above code snippet is useful even just for educational purposes as it can show you  like x-ray  how many threads you actually have  versus how many you thought you have - quite often those two are different numbers

User · Answer

IRB has a setting for this awful  feature   which you can customize   Create a file called    irbrc that includes the following line   IRB conf  BACK TRACE LIMIT    100   This will allow you to see 100 stack frames in irb  at least  I haven t been able to find an equivalent setting for the non-interactive runtime   Detailed information about IRB customization can be found in the Pickaxe book

User · Answer

One liner for callstack   begin  Whatever you want  rescue   gt  e  puts e message  puts  puts e backtrace  end   One liner for callstack without all the gems s   begin  Whatever you want  rescue   gt  e  puts e message  puts  puts e backtrace grep v    gems      end   One liner for callstack without all the gems s and relative to current directory  begin  Whatever you want  rescue   gt  e  puts e message  puts  puts e backtrace grep v    gems     map    l  l gsub  pwd  strip               end

User · Answer

One liner for callstack   begin  Whatever you want  rescue   gt  e  puts e message  puts  puts e backtrace  end   One liner for callstack without all the gems s   begin  Whatever you want  rescue   gt  e  puts e message  puts  puts e backtrace grep v    gems      end   One liner for callstack without all the gems s and relative to current directory  begin  Whatever you want  rescue   gt  e  puts e message  puts  puts e backtrace grep v    gems     map    l  l gsub  pwd  strip               end

User · Answer

You can also use backtrace Ruby gem  I m the author    require  backtrace  begin     do something dangerous rescue StandardError   gt  e   puts Backtrace new e  end

User · Answer

Exception backtrace has the entire stack in it   def do division by zero  5   0  end begin   do division by zero rescue   gt  exception   puts exception backtrace   raise   always reraise end    Inspired by Peter Cooper s Ruby Inside blog

User · Answer

examine all threads backtraces to find the culprit  Even fully expanded call stack can still hide the actual offending line of code from you when you use more than one thread   Example  One thread is iterating ruby Hash  other thread is trying to modify it  BOOM  Exception  And the problem with the stack trace you get while trying to modify  busy  hash is that it shows you chain of functions down to the place where you re trying to modify hash  but it does NOT show who s currently iterating it in parallel  who owns it   Here s the way to figure that out by printing stack trace for ALL currently running threads  Here s how you do this     This solution was found in comment by  thedarkone on https   github com rails rails issues 24627 rescue Object   gt  boom      thread count   0     Thread list each do  t        thread count    1       err msg     --- thread   thread count  of total   Thread list size    t object id  backtrace begin  n          Lets see if we are able to pin down the culprit         by collecting backtrace for all existing threads        err msg    t backtrace join   n         err msg      n---thread   thread count  of total   Thread list size    t object id  backtrace end  n      end        and just print it somewhere you like       stderr puts err msg       raise   always reraise end   The above code snippet is useful even just for educational purposes as it can show you  like x-ray  how many threads you actually have  versus how many you thought you have - quite often those two are different numbers

User · Answer

Exception backtrace has the entire stack in it   def do division by zero  5   0  end begin   do division by zero rescue   gt  exception   puts exception backtrace   raise   always reraise end    Inspired by Peter Cooper s Ruby Inside blog

User · Answer

I was getting these errors when trying to load my test environment  via rake test or autotest  and the IRB suggestions didn t help   I ended up wrapping my entire test test helper rb in a begin rescue block and that fixed things up   begin   class ActiveSupport  TestCase      awesome stuff   end rescue   gt  e   puts e backtrace end

User · Answer

Almost everybody answered this  My version of printing any rails exception into logs would be  begin     some statement rescue   gt  e     puts  quot Exception Occurred   e   Message    e message   Backtrace    n   e backtrace join  quot  n quot    quot      Rails logger error  quot Exception Occurred   e   Message    e message   Backtrace    n   e backtrace join  quot  n quot    quot  end

User · Answer

This mimics the official Ruby trace  if that s important to you   begin   0 0    or some other nonsense rescue   gt  e   puts e backtrace join   n t           sub   n t        e   e class        e class          n t   end   Amusingly  it doesn t handle  unhandled exception  properly  reporting it as  RuntimeError   but the location is correct

User · Answer

I was getting these errors when trying to load my test environment  via rake test or autotest  and the IRB suggestions didn t help   I ended up wrapping my entire test test helper rb in a begin rescue block and that fixed things up   begin   class ActiveSupport  TestCase      awesome stuff   end rescue   gt  e   puts e backtrace end

User · Answer

Exception backtrace has the entire stack in it   def do division by zero  5   0  end begin   do division by zero rescue   gt  exception   puts exception backtrace   raise   always reraise end    Inspired by Peter Cooper s Ruby Inside blog

User · Answer

This produces the error description and nice clean  indented stacktrace   begin                   Some exception throwing code rescue   gt  e   puts  Error during processing           puts  Backtrace  n t  e backtrace join   n t     end

User · Answer

You could also do this if you d like a simple one-liner   puts caller

User · Answer

Almost everybody answered this  My version of printing any rails exception into logs would be  begin     some statement rescue   gt  e     puts  quot Exception Occurred   e   Message    e message   Backtrace    n   e backtrace join  quot  n quot    quot      Rails logger error  quot Exception Occurred   e   Message    e message   Backtrace    n   e backtrace join  quot  n quot    quot  end

[ruby] How do I get ruby to print a full backtrace instead of a truncated one?

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