[ros-users] Race condition in actionlib
Ryan Miller
rmiller4589 at gmail.com
Fri Apr 1 22:01:04 UTC 2011
Hi Vijay,
A few questions then. Is it acceptable for messages to be dropped? I thought
actionlib used reliable data transfer. In my actual program, I am depending
on every message being sent, and I would rather not use delays and risk my
robot still locking up.
To give you some perspective, I am using the client to plan a path to a
destination, and I am using the server to execute the motor controls to
drive on a path it is given. Using a timeout would be fine (it's what I'm
doing in my production code, actually). But with this new result, it seems I
should now cancel the goal any time waitForResult times out because I don't
know if the server is just taking a long time or if its message was dropped
and it's actually finished. What I was planning on doing was letting the
motion planner follow the path until it is in imminent danger of colliding
with something, in which case I would cancel the goal. Unfortunately, I have
a new problem now where I cannot even cancel the goal.
After timing out, the client always thinks it's goal is active, and I am
unable to cancel the goal. The output I am getting from the attached example
is:
--- snip ---
*[ INFO] [1301694170.491982098]: Sending goal
[ INFO] [1301694170.492052098]: Waiting for result...
[ INFO] [1301694170.492138988]: Server is aborting goal.
[ INFO] [1301694170.492193892]: After waiting for the result, the state is
ABORTED
[ INFO] [1301694170.492232340]: Sending goal
[ INFO] [1301694170.492279138]: Waiting for result...
[ INFO] [1301694170.492341676]: Server is aborting goal.
[ INFO] [1301694170.492388975]: After waiting for the result, the state is
ABORTED*
[ INFO] [1301694170.492443452]: Sending goal
[ INFO] [1301694170.492543467]: Server is aborting goal.
[ INFO] [1301694170.492620163]: Waiting for result...
[ INFO] [1301694171.492789064]: After waiting for the result, the state is
ACTIVE
[ INFO] [1301694171.492909135]: Timeout, cancelling the goal
*[ INFO] [1301694171.492953475]: After cancelling, the state is ACTIVE*
*[ INFO] [1301694171.492977808]: The server is not done.
[ INFO] [1301694172.493114619]: The server is not done.
[ INFO] [1301694173.493301543]: The server is not done.
[ INFO] [1301694174.493476758]: The server is not done.*
^C
--- snip ---
(Normal behaviour is italicised. Unexpected behaviour is bold)
Might this be another problem, or am I misusing SimpleActionClient?
Thanks again,
-Ryan
On Fri, Apr 1, 2011 at 4:54 PM, Vijay Pradeep <vpradeep at willowgarage.com>wrote:
> Hi Ryan,
>
> Ok, I think we're actually getting somewhere.....
>
>
> > When I move the called to spinner.start() to where you suggested, the
> client gets stuck on its call to waitForServer as follows:
> Totally my bad. What I meant for you to do was the following:
> 1) Construct client & server
> 2) Spin up threads
> 3) waitForServer
> 4) Start sending goals
>
> To do this, you'll have to move spinner.start() to where I suggested, and
> also move client_.waitForServer() to the top of run(). Currently, the app
> is trying to waitForServer without any spin threads running, which is
> causing it to get stuck. Sorry about that. I'd also suggest trying to run
> with 1 spinner instead of 4, and see if that helps.
>
> Thanks for the gdb thread info. It looks like all the threads we're
> worried about are happily waiting for inputs in pthread conditions. This
> makes it seem even more like a message was being dropped.
>
> Also, I finally got it to freeze on my side, *with* debug on. See output:
>
> Done.
> [ INFO] [1301690082.884716841]: Hogging time or something
> Current State: ABORTED
> [DEBUG] [1301690082.884784275]: IN DELETER
> [DEBUG] [1301690082.884838215]: About to erase CommStateMachine
> [DEBUG] [1301690082.884891598]: Done erasing CommStateMachine
> [DEBUG] [1301690082.884948750]: about to start initGoal()
> [DEBUG] [1301690082.885037423]: The action server has received a new goal
> request
> [DEBUG] [1301690082.885152395]: A new goal has been recieved by the single
> goal action server
> [DEBUG] [1301690082.885263065]: Accepting a new goal
> [DEBUG] [1301690082.885330292]: Accepting goal, id:
> /test_client_server-281-1301690082.884983820, stamp: 1301690082.88
> Server called. Aborting goal.
> [DEBUG] [1301690082.885555049]: Setting the current goal as aborted
> [DEBUG] [1301690082.885618287]: Setting status to aborted on goal, id:
> /test_client_server-281-1301690082.884983820, stamp: 1301690082.88
> [DEBUG] [1301690082.885675967]: Publishing result for goal with id:
> /test_client_server-281-1301690082.884983820 and stamp: 1301690082.88
> [DEBUG] [1301690082.885743824]: Getting status over the wire.
> [DEBUG] [1301690082.885956181]: Done with initGoal()
> [DEBUG] [1301690082.887905041]: Getting status over the wire.
> [DEBUG] [1301690082.888000669]: Trying to transition to ACTIVE
> [DEBUG] [1301690082.888064094]: Transitioning CommState from
> WAITING_FOR_GOAL_ACK to ACTIVE
> [DEBUG] [1301690082.888130878]: Transitioning SimpleState from [PENDING] to
> [ACTIVE]
> Active.
> [DEBUG] [1301690082.888203846]: Trying to transition to WAITING_FOR_RESULT
> *[DEBUG] [1301690082.888262411]: Transitioning CommState from ACTIVE to
> WAITING_FOR_RESULT*
> [DEBUG] [1301690083.088191441]: Getting status over the wire.
> [DEBUG] [1301690083.288523198]: Getting status over the wire.
> [DEBUG] [1301690083.488836856]: Getting status over the wire.
> [DEBUG] [1301690083.688115542]: Getting status over the wire.
> [DEBUG] [1301690083.888460218]: Getting status over the wire.
> [DEBUG] [1301690084.088794991]: Getting status over the wire.
> [DEBUG] [1301690084.288137860]: Getting status over the wire.
> [DEBUG] [1301690084.488456451]: Getting status over the wire.
> [DEBUG] [1301690084.688742829]: Getting status over the wire.
> [DEBUG] [1301690084.888085527]: Getting status over the wire.
> [DEBUG] [1301690085.088418107]: Getting status over the wire.
>
> On the client side, the goal transitioned to WAITING_FOR_RESULT, which
> means that the server successfully set the goal to a terminal state (in this
> case, ABORTED). However, for some reason, the client never gets the result
> message. With so many messages flying across so quickly, I guess one of the
> result messages happens to get dropped. This also explains why adding a
> sleep in the server callback stopped the freezing. The sleep significantly
> slowed down the messaging rate, preventing the result message from being
> dropped.
>
> It is definitely best practice to always add a timeout to waitForResult().
> I've updated the actionlib quickstart guide<http://www.ros.org/wiki/actionlib#C.2B-.2B-_SimpleActionClient>accordingly.
>
> And, please let me know if any of the spinner tweaks I suggested make a
> difference.
>
> Vijay
>
>
> On Fri, Apr 1, 2011 at 1:07 PM, Ryan Miller <rmiller4589 at gmail.com> wrote:
>
>> Hi Vijay,
>>
>> When I move the called to spinner.start() to where you suggested, the
>> client gets stuck on its call to waitForServer as follows:
>>
>> --- snip ---
>> $ rosrun chores chores
>> [DEBUG] [1301684841.767308639]: Spinning up a thread for the
>> SimpleActionClient
>> [DEBUG] [1301684841.794376567]: goalConnectCallback: Adding
>> [/test_client_server] to goalSubscribers
>> [DEBUG] [1301684841.794470922]: Goal Subscribers (1 total)
>> - /test_client_server
>> [DEBUG] [1301684841.800129524]: cancelConnectCallback: Adding
>> [/test_client_server] to cancelSubscribers
>> [DEBUG] [1301684841.800199855]: cancel Subscribers (1 total)
>> - /test_client_server
>> [DEBUG] [1301684841.809336199]: isServerConnected: Didn't receive status
>> yet, so not connected yet
>> [DEBUG] [1301684841.809441030]: isServerConnected: Didn't receive status
>> yet, so not connected yet
>> [DEBUG] [1301684842.309665431]: isServerConnected: Didn't receive status
>> yet, so not connected yet
>> [DEBUG] [1301684842.810034890]: isServerConnected: Didn't receive status
>> yet, so not connected yet
>> ...
>> [DEBUG] [1301684842.810034890]: isServerConnected: Didn't receive status
>> yet, so not connected yet
>> --- snip ---
>>
>> Also, it appears I have a heisenbug on my hands because when I turn on
>> rosconsole debugging, the problem seemingly disappears, but when I keep it
>> off, it crashes on almost every run. By the way, the single call to ROS_INFO
>> I placed in the code is critical to making the program halt more often.
>> Remove that, and you'll have more trouble getting the program to halt.
>>
>> Is there any other information that might help you replicate this problem?
>> For now, I'll just throw some facts here about the computer I'm using. I am
>> running Ubuntu 10.10 64-bit. I have replicated the problem on a relatively
>> slow laptop and two pretty fast desktops. The specific package information
>> for the version of ros-diamondback-common I am using is:
>>
>> --- snip ---
>> $ dpkg -s ros-diamondback-common
>> Package: ros-diamondback-common
>> Status: install ok installed
>> Priority: optional
>> Section: unknown
>> Installed-Size: 34224
>> Maintainer: Tully Foote tfoote at willowgarage.com
>> Architecture: amd64
>> Version: 1.4.3-s1299027665~maverick
>> Depends: ros-diamondback-common-msgs (= 1.4.0-s1299027564~maverick),
>> ros-diamondback-ros (= 1.4.6-s1298587732~maverick), ros-diamondback-ros-comm
>> (= 1.4.5-s1299027222~maverick), libc6, build-essential, cmake, python-yaml,
>> subversion, uuid-dev, libcppunit-dev
>> Description: common code for personal robots
>> This stack contains tools built on top of ROS core which are commonly used
>> throughout the ROS ecosystem.
>> Wg-Rosdistro: diamondback
>> --- snip ---
>>
>> Here is some information from gdb from when the program halts. I've
>> printed a list of the running threads as well as the backtraces of a few of
>> the ones in different functions.
>>
>> --- snip ---
>> Current State: ABORTED
>> Server called. Aborting goal.
>> Active.
>> ^C
>> Program received signal SIGINT, Interrupt.
>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 212 ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: No
>> such file or directory.
>> in ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S
>> (gdb) info thread
>> 12 Thread 0x7fffecea2700 (LWP 9649) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 11 Thread 0x7fffed6a3700 (LWP 9646) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 10 Thread 0x7fffedea4700 (LWP 9640) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 9 Thread 0x7fffee6a5700 (LWP 9639) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 8 Thread 0x7fffeeea6700 (LWP 9638) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 7 Thread 0x7fffef6a7700 (LWP 9637) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 6 Thread 0x7fffefea8700 (LWP 9636) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 5 Thread 0x7ffff06a9700 (LWP 9635) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 4 Thread 0x7ffff0eaa700 (LWP 9630) pthread_cond_wait@@GLIBC_2.3.2 () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
>> 3 Thread 0x7ffff16ab700 (LWP 9629) 0x00007ffff534e2c3 in select () at
>> ../sysdeps/unix/syscall-template.S:82
>> 2 Thread 0x7ffff1eac700 (LWP 9628) 0x00007ffff5349203 in __poll
>> (fds=<value optimized out>, nfds=<value optimized out>, timeout=100) at
>> ../sysdeps/unix/sysv/linux/poll.c:87
>> * 1 Thread 0x7ffff7fcd760 (LWP 9609) pthread_cond_timedwait@@GLIBC_2.3.2
>> () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> (gdb) bt
>> #0 pthread_cond_timedwait@@GLIBC_2.3.2 () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> #1 0x000000000044c698 in timed_wait<boost::unique_lock<boost::mutex> >
>> (this=0x7fffffffe110, m=..., wait_duration=<value optimized out>) at
>> /usr/include/boost/thread/pthread/condition_variable.hpp:110
>> #2
>> boost::condition_variable_any::timed_wait<boost::unique_lock<boost::mutex>,
>> boost::posix_time::milliseconds> (this=0x7fffffffe110, m=...,
>> wait_duration=<value optimized out>)
>> at /usr/include/boost/thread/pthread/condition_variable.hpp:133
>> #3 0x000000000044d355 in
>> actionlib::SimpleActionClient<chores::DoDishesAction_<std::allocator<void> >
>> >::waitForResult (this=0x7fffffffe040, timeout=...)
>> at
>> /opt/ros/diamondback/stacks/common/actionlib/include/actionlib/client/simple_action_client.h:567
>> #4 0x00000000004583f6 in ClientGuy::run (this=0x7fffffffe040) at
>> /home/pesckal/prometheus/ros/chores/src/main.cpp:50
>> #5 0x000000000042d8d5 in main (argc=1, argv=<value optimized out>) at
>> /home/pesckal/prometheus/ros/chores/src/main.cpp:87
>> (gdb) thread 2
>> [Switching to thread 2 (Thread 0x7ffff1eac700 (LWP 9628))]#0
>> 0x00007ffff5349203 in __poll (fds=<value optimized out>, nfds=<value
>> optimized out>, timeout=100) at ../sysdeps/unix/sysv/linux/poll.c:87
>> 87 ../sysdeps/unix/sysv/linux/poll.c: No such file or directory.
>> in ../sysdeps/unix/sysv/linux/poll.c
>> (gdb) bt
>> #0 0x00007ffff5349203 in __poll (fds=<value optimized out>, nfds=<value
>> optimized out>, timeout=100) at ../sysdeps/unix/sysv/linux/poll.c:87
>> #1 0x00007ffff78c169a in ros::PollSet::update (this=0x69c650,
>> poll_timeout=100)
>> at
>> /tmp/buildd/ros-diamondback-ros-comm-1.4.5/debian/ros-diamondback-ros-comm/opt/ros/diamondback/stacks/ros_comm/clients/cpp/roscpp/src/libros/poll_set.cpp:202
>> #2 0x00007ffff7906778 in ros::PollManager::threadFunc (this=0x69c650)
>> at
>> /tmp/buildd/ros-diamondback-ros-comm-1.4.5/debian/ros-diamondback-ros-comm/opt/ros/diamondback/stacks/ros_comm/clients/cpp/roscpp/src/libros/poll_manager.cpp:95
>> #3 0x00007ffff6df5230 in thread_proxy () from
>> /usr/lib/libboost_thread.so.1.42.0
>> #4 0x00007ffff55f9971 in start_thread (arg=<value optimized out>) at
>> pthread_create.c:304
>> #5 0x00007ffff535592d in clone () at
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
>> #6 0x0000000000000000 in ?? ()
>> (gdb) thread 3
>> [Switching to thread 3 (Thread 0x7ffff16ab700 (LWP 9629))]#0
>> 0x00007ffff534e2c3 in select () at ../sysdeps/unix/syscall-template.S:82
>> 82 ../sysdeps/unix/syscall-template.S: No such file or directory.
>> in ../sysdeps/unix/syscall-template.S
>> (gdb) bt
>> #0 0x00007ffff534e2c3 in select () at
>> ../sysdeps/unix/syscall-template.S:82
>> #1 0x00007ffff723313a in XmlRpc::XmlRpcDispatch::work (this=0x69ac18,
>> timeout=<value optimized out>)
>> at
>> /tmp/buildd/ros-diamondback-ros-comm-1.4.5/debian/ros-diamondback-ros-comm/opt/ros/diamondback/stacks/ros_comm/utilities/xmlrpcpp/src/XmlRpcDispatch.cpp:110
>> #2 0x00007ffff7903de9 in ros::XMLRPCManager::serverThreadFunc
>> (this=0x69abc0)
>> at
>> /tmp/buildd/ros-diamondback-ros-comm-1.4.5/debian/ros-diamondback-ros-comm/opt/ros/diamondback/stacks/ros_comm/clients/cpp/roscpp/src/libros/xmlrpc_manager.cpp:256
>> #3 0x00007ffff6df5230 in thread_proxy () from
>> /usr/lib/libboost_thread.so.1.42.0
>> #4 0x00007ffff55f9971 in start_thread (arg=<value optimized out>) at
>> pthread_create.c:304
>> #5 0x00007ffff535592d in clone () at
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
>> #6 0x0000000000000000 in ?? ()
>> (gdb) thread 4
>> [Switching to thread 4 (Thread 0x7ffff0eaa700 (LWP 9630))]#0
>> pthread_cond_wait@@GLIBC_2.3.2 () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
>> 162 ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: No such
>> file or directory.
>> in ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
>> (gdb) bt
>> #0 pthread_cond_wait@@GLIBC_2.3.2 () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
>> #1 0x00007ffff79603b3 in wait (this=<value optimized out>) at
>> /usr/include/boost/thread/pthread/condition_variable.hpp:20
>> #2 ros::ROSOutAppender::logThread (this=<value optimized out>)
>> at
>> /tmp/buildd/ros-diamondback-ros-comm-1.4.5/debian/ros-diamondback-ros-comm/opt/ros/diamondback/stacks/ros_comm/clients/cpp/roscpp/src/libros/rosout_appender.cpp:135
>> #3 0x00007ffff6df5230 in thread_proxy () from
>> /usr/lib/libboost_thread.so.1.42.0
>> #4 0x00007ffff55f9971 in start_thread (arg=<value optimized out>) at
>> pthread_create.c:304
>> #5 0x00007ffff535592d in clone () at
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
>> #6 0x0000000000000000 in ?? ()
>> (gdb) thread 5
>> [Switching to thread 5 (Thread 0x7ffff06a9700 (LWP 9635))]#0
>> pthread_cond_timedwait@@GLIBC_2.3.2 () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> 212 ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S: No
>> such file or directory.
>> in ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S
>> (gdb) bt
>> #0 pthread_cond_timedwait@@GLIBC_2.3.2 () at
>> ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:212
>> #1 0x00007ffff796885d in bool
>> boost::condition_variable::timed_wait<boost::date_time::subsecond_duration<boost::posix_time::time_duration,
>> 1000000l> >(boost::unique_lock<boost::mutex>&,
>> boost::date_time::subsecond_duration<boost::posix_time::time_duration,
>> 1000000l> const&) () from
>> /opt/ros/diamondback/stacks/ros_comm/clients/cpp/roscpp/lib/libros.so
>> #2 0x00007ffff7964e99 in ros::CallbackQueue::callAvailable
>> (this=0x69c410, timeout=DWARF-2 expression error: DW_OP_reg operations must
>> be used either alone or in conjuction with DW_OP_piece or DW_OP_bit_piece.
>> )
>> at
>> /tmp/buildd/ros-diamondback-ros-comm-1.4.5/debian/ros-diamondback-ros-comm/opt/ros/diamondback/stacks/ros_comm/clients/cpp/roscpp/src/libros/callback_queue.cpp:307
>> #3 0x00007ffff78f22e1 in ros::internalCallbackQueueThreadFunc ()
>> at
>> /tmp/buildd/ros-diamondback-ros-comm-1.4.5/debian/ros-diamondback-ros-comm/opt/ros/diamondback/stacks/ros_comm/clients/cpp/roscpp/src/libros/init.cpp:265
>> #4 0x00007ffff6df5230 in thread_proxy () from
>> /usr/lib/libboost_thread.so.1.42.0
>> #5 0x00007ffff55f9971 in start_thread (arg=<value optimized out>) at
>> pthread_create.c:304
>> #6 0x00007ffff535592d in clone () at
>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
>> #7 0x0000000000000000 in ?? ()
>> (gdb)
>> --- snip ---
>>
>> Also, I'm sorry to hear you had to create a new package to compile the
>> program. As a sanity check, I also created a new package and copied over the
>> cpp and action files, but this did not change the result I was having, as
>> expected. (I've attached the package, for reference.)
>>
>> I really appreciate the help, thank you.
>>
>> -Ryan
>>
>>
>> On Fri, Apr 1, 2011 at 2:03 PM, Vijay Pradeep <vpradeep at willowgarage.com>
>> wrote:
>> > Hi Ryan,
>> >
>> > Here's one more thing to try. Turn on rosconsole debugging (See
>> rosconole
>> > configuration)
>> >
>> > You're going to want the following two lines in your rosonsole.config:
>> > log4j.logger.ros.actionlib=DEBUG
>> > log4j.logger.ros.chores=DEBUG
>> >
>> >
>> > You'll get an output that looks like this:
>> > [DEBUG] [1301680806.580203868]: Setting the current goal as aborted
>> > [DEBUG] [1301680806.580254603]: Setting status to aborted on goal, id:
>> > /test_client_server-1118-1301680806.579359151, stamp: 1301680806.58
>> > [DEBUG] [1301680806.580301868]: Publishing result for goal with id:
>> > /test_client_server-1118-1301680806.579359151 and stamp: 1301680806.58
>> > [DEBUG] [1301680806.580439068]: Getting status over the wire.
>> > [DEBUG] [1301680806.580509625]: Trying to transition to ACTIVE
>> > [DEBUG] [1301680806.580553872]: Transitioning CommState from
>> > WAITING_FOR_GOAL_ACK to ACTIVE
>> > [DEBUG] [1301680806.580603042]: Transitioning SimpleState from [PENDING]
>> to
>> > [ACTIVE]
>> > Active.
>> > [DEBUG] [1301680806.580934461]: Trying to transition to
>> WAITING_FOR_RESULT
>> > [DEBUG] [1301680806.580991611]: Transitioning CommState from ACTIVE to
>> > WAITING_FOR_RESULT
>> > [DEBUG] [1301680806.581051376]: Trying to transition to DONE
>> > [DEBUG] [1301680806.581108948]: Transitioning CommState from
>> > WAITING_FOR_RESULT to DONE
>> > [DEBUG] [1301680806.581164618]: Transitioning SimpleState from [ACTIVE]
>> to
>> > [DONE]
>> > Done.
>> > [ INFO] [1301680806.581243326]: Hogging time or something
>> > Current State: ABORTED
>> > [DEBUG] [1301680806.581302953]: IN DELETER
>> > [DEBUG] [1301680806.581339010]: About to erase CommStateMachine
>> > [DEBUG] [1301680806.581377433]: Done erasing CommStateMachine
>> > [DEBUG] [1301680806.581414297]: about to start initGoal()
>> > [DEBUG] [1301680806.581489440]: Done with initGoal()
>> > [DEBUG] [1301680806.581544720]: The action server has received a new
>> goal
>> > request
>> > [DEBUG] [1301680806.581638097]: A new goal has been recieved by the
>> single
>> > goal action server
>> > [DEBUG] [1301680806.581705716]: Accepting a new goal
>> > [DEBUG] [1301680806.581758609]: Accepting goal, id:
>> > /test_client_server-1119-1301680806.581440270, stamp: 1301680806.58
>> > Server called. Aborting goal.
>> >
>> > Can send me the debug output for the last few cycles when your app
>> freezes?
>> >
>> > Vijay
>> >
>> > On Fri, Apr 1, 2011 at 10:05 AM, Vijay Pradeep <
>> vpradeep at willowgarage.com>
>> > wrote:
>> >>
>> >> Hi Ryan,
>> >>
>> >> So I actually ran your original chores app overnight (~10 hours), and
>> it
>> >> still didn't freeze.
>> >>
>> >> Also, right now, I tried running your new chores app about 30 times
>> (for
>> >> about 5 seconds on each run), and it still hadn't frozen. I couldn't
>> get
>> >> the app to build using your CMakeLists and Makefile, so I rewrote them
>> based
>> >> on the standard "roscreate-pkg" versions of these files. I doubt this
>> would
>> >> affect the functionality.
>> >>
>> >> The fact that it freezes close to startup is interesting. My guess
>> would
>> >> be that it is having some sort of startup interaction with the
>> AsyncSpinner.
>> >>
>> >> Instead of:
>> >> int main(int argc, char** argv) {
>> >> ros::init(argc, argv, "test_client_server");
>> >>
>> >> ros::AsyncSpinner spinner(4);
>> >> spinner.start();
>> >>
>> >> ServerDude sd;
>> >>
>> >> ClientGuy client;
>> >> client.run();
>> >>
>> >> return 0;
>> >> }
>> >>
>> >> Can you try:
>> >> int main(int argc, char** argv) {
>> >> ros::init(argc, argv, "test_client_server");
>> >>
>> >> ros::AsyncSpinner spinner(4);
>> >>
>> >> ServerDude sd;
>> >>
>> >> ClientGuy client;
>> >> spinner.start();
>> >> client.run();
>> >>
>> >> return 0;
>> >> }
>> >>
>> >> I would really like to get to the bottom of this, but it's hard to do
>> much
>> >> on my end if I can't actually get it to halt.
>> >>
>> >> Vijay
>> >>
>> >> On Fri, Apr 1, 2011 at 7:51 AM, Ryan Miller <rmiller4589 at gmail.com>
>> wrote:
>> >>>
>> >>> Hey Vijay, thanks for helping (and sorry for the double post; I
>> >>> accidentally forgot to reply all, and I figure some people on the list
>> >>> may be interested in the email). Yes, I did mean waitForResult, and I
>> >>> am also using common-1.4.3 (diamondback too, if that's relevant).
>> >>> Since you're having trouble duplicating the issue, I went back to
>> >>> create an example closer to what I'm actually doing, and I managed to
>> >>> get it to crash just as often. I've attached the project.
>> >>>
>> >>> If it doesn't crash after about 5 seconds, restart it. It seems if it
>> >>> continues for more than 5 seconds, it is more likely to continue
>> >>> running for much longer, but it usually halts within a second.
>> >>>
>> >>> Thanks a ton.
>> >>>
>> >>> -Ryan
>> >>>
>> >>> On Thu, Mar 31, 2011 at 11:00 PM, Vijay Pradeep
>> >>> <vpradeep at willowgarage.com> wrote:
>> >>> > Hi Ryan,
>> >>> >
>> >>> > I'm sorry that you're having trouble getting actionlib to work.
>> What
>> >>> > version of the common stack do you have?
>> >>> >
>> >>> > Note that it is always possible for some of the ROS messages to be
>> >>> > dropped.
>> >>> > If the result message doesn't make it to the action client, then
>> >>> > waitForResult is going to block forever. I'd suggest adding a
>> timeout
>> >>> > on
>> >>> > waitForServer, and then preempting the goal if you end up waiting
>> too
>> >>> > long.
>> >>> >
>> >>> >> I made each callback print when
>> >>> >> it was called, and I found that quite often, the program would
>> block
>> >>> >> forever when I called waitForServer.
>> >>> > I'm guessing you meant "the program would block forever when I
>> called
>> >>> > waitForResult"
>> >>> >
>> >>> > I'm using common-1.4.3, and after running your example for ~10
>> minutes,
>> >>> > it
>> >>> > doesn't seem to freeze for me. I can rerun this test with the exact
>> >>> > version
>> >>> > of common that you're using. Is there anything you can do to make
>> this
>> >>> > minimal example freeze more often? Are there some strategic sleeps
>> you
>> >>> > could
>> >>> > add to make it mimic your original app more closely?
>> >>> >
>> >>> > If you can get the chores app to freeze, you could try attaching gdb
>> to
>> >>> > the
>> >>> > process and seeing where all the threads are (using the "info
>> threads"
>> >>> > command inside gdb). A bunch of them will be stuck on
>> >>> > pthread_cond_timedwait calls, but I'd be curious if there's a thread
>> >>> > stuck
>> >>> > on a lock inside of actionlib. That would be indicative of a race
>> >>> > condition
>> >>> > in actionlib.
>> >>> >
>> >>> > Vijay
>> >>> >
>> >>> > On Thu, Mar 31, 2011 at 6:55 PM, Ryan Miller <rmiller4589 at gmail.com
>> >
>> >>> > wrote:
>> >>> >>
>> >>> >> Because of a timing issue I can't quite pin down, actionlib
>> >>> >> occasionally appears to exhibit a race condition. I found the
>> problem
>> >>> >> after adding callbacks to my client. I made each callback print
>> when
>> >>> >> it was called, and I found that quite often, the program would
>> block
>> >>> >> forever when I called waitForServer. The problem was that the
>> client's
>> >>> >> active callback was called but the server's execute method was
>> never
>> >>> >> called.
>> >>> >>
>> >>> >> I have reduced the problem into a simple ROS package with a single
>> >>> >> executable that I have attached. After running the node for a
>> while, I
>> >>> >> finally noticed the same problem. It's last output before blocking
>> >>> >> was:
>> >>> >>
>> >>> >> --- snip ---
>> >>> >> Current State: ABORTED
>> >>> >> Aborting.
>> >>> >> Active.
>> >>> >> Done.
>> >>> >> Current State: ABORTED
>> >>> >> Aborting.
>> >>> >> Active.
>> >>> >> --- snip ---
>> >>> >>
>> >>> >> In my actual code, the condition happens extremely frequently, but
>> I
>> >>> >> found I could mitigate the problem by sleeping for one millisecond
>> >>> >> before returning from the server's execute method. (I should warn
>> you
>> >>> >> that in the attached example, the problem almost never occurs).
>> >>> >>
>> >>> >> Is this likely a bug, or might I doing something wrong? Any
>> >>> >> suggestions would be appreciated. Thanks for the help.
>> >>> >>
>> >>> >> -Ryan
>> >>> >>
>> >>> >> _______________________________________________
>> >>> >> ros-users mailing list
>> >>> >> ros-users at code.ros.org
>> >>> >> https://code.ros.org/mailman/listinfo/ros-users
>> >>> >>
>> >>> >
>> >>> >
>> >>> >
>> >>> > --
>> >>> > Vijay Pradeep
>> >>> > Systems Engineer
>> >>> > Willow Garage, Inc.
>> >>> > vpradeep at willowgarage.com
>> >>> >
>> >>> >
>> >>
>> >>
>> >>
>> >> --
>> >> Vijay Pradeep
>> >> Systems Engineer
>> >> Willow Garage, Inc.
>> >> vpradeep at willowgarage.com
>> >>
>> >
>> >
>> >
>> > --
>> > Vijay Pradeep
>> > Systems Engineer
>> > Willow Garage, Inc.
>> > vpradeep at willowgarage.com
>> >
>> >
>>
>>
>
>
> --
> Vijay Pradeep
> Systems Engineer
> Willow Garage, Inc.
> <tfoote at willowgarage.com>vpradeep at willowgarage.com
>
>
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