Reading subprocess stdout susceptible to deadlock

[Vitaly Davidovich]

Hi all,

Just wanted to revisit this issue again.  I haven't filed a JBS entry for
it, primarily because I'd like some validation/confirmation/hunch that this
is, indeed, a bug before proceeding.  Does anyone have thoughts on this
scenario?

Thanks

On Wed, Mar 30, 2016 at 10:45 AM, Vitaly Davidovich <vitalyd at gmail.com>
wrote:

> Hi Roger,
>
> The stack traces are:
>
> "process reaper" #44 daemon prio=10 os_prio=0 tid=0x0000000004083000 nid=0x7b1c waiting for monitor entry [0x00002b703ffbe000]
>
>    java.lang.Thread.State: BLOCKED (on object monitor)
>
>         at java.lang.UNIXProcess$ProcessPipeInputStream.processExited(UNIXProcess.java:528)
>
>         - waiting to lock <0x00000000aba7a790> (a java.lang.UNIXProcess$ProcessPipeInputStream)
>
>         at java.lang.UNIXProcess.lambda$initStreams$275(UNIXProcess.java:299)
>
>         at java.lang.UNIXProcess$$Lambda$10/523574157.run(Unknown Source)
>
>         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
>
>
>
>
>
> "pool-1-thread-1" #43 prio=5 os_prio=0 tid=0x0000000003ee3800 nid=0x7b13 runnable [0x00002b7050837000]
>
>    java.lang.Thread.State: RUNNABLE
>
>         at java.io.FileInputStream.readBytes(Native Method)
>
>         at java.io.FileInputStream.read(FileInputStream.java:255)
>
>         at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
>
>         at java.io.BufferedInputStream.read1(BufferedInputStream.java:286)
>
>         at java.io.BufferedInputStream.read(BufferedInputStream.java:345)
>
>         - locked <0x00000000aba7a790> (a java.lang.UNIXProcess$ProcessPipeInputStream)
>
>         at SomeClass.callReadOnInputStream()
>
>
> SomeClass.callReadOnInputStream() is something that invokes
> InputStream.read(byte[], int, int) on the stream.
>
> Thanks
>
>
> On Wed, Mar 30, 2016 at 10:09 AM, Roger Riggs <Roger.Riggs at oracle.com>
> wrote:
>
>> Hi Vitaly,
>>
>> I haven't seen that before, please create a bug and include the stack
>> traces.
>>
>> Thanks, Roger
>>
>>
>>
>> On 3/30/2016 9:56 AM, Vitaly Davidovich wrote:
>>
>>> Hi,
>>>
>>> It seems that doing a blocking read on a subprocess's stdout can lead to
>>> deadlock between the thread doing the read and the process reaper thread.
>>> The deadlock occurs because the reader is synchronized on the
>>> ProcessPipeInputStream, blocks for more data to consume, and process
>>> reaper
>>> comes along trying to call processExited, which also synchronizes on the
>>> same PPIS.  The reader appears stuck because it's not seeing the EOF due
>>> to
>>> process reaper not being able to close the stream.
>>>
>>> I couldn't find any existing reports of this via quick search, which
>>> makes
>>> me wonder if I'm missing something.  Is this a known issue?
>>>
>>> Thanks
>>>
>>>
>>>
>>
>