Re: Boost:1.82.0 ASIO changed its behavior

From: Pavel Vazharov (freakpv_at_[hidden])
Date: 2025-05-21 04:04:39

Hi,
May I ask few questions just for clarification of the situation:
On Tue, May 20, 2025 at 4:03 PM Nedelin Rusev via Boost-users <
boost-users_at_[hidden]> wrote:

> Hi,
>
> Recently I inherited an old project, which uses boost 1.65.0 and ASIO, for
> custom implementation of the SCTP protocol.
> Technically it adapts the existing ASIO TCP for SCTP. Another
> implementation uses this ASIO-SCTP to asynchronously send
> and receive data. My task was to make both implementations work with any
> boost version from 1.65.0 to 1.87.0.
>
> I did the necessary changes and the project now compiles and runs, but I
> face a test deviation with boost versions
> 1.82.0 and above.
>
> The test is more or less simple:
> - we have pre-generated data
> - we start a server, which only receives data and stores it in file per
> connected client
> - we start multiple clients, each running in its own thread. Each client
> sends its own data to the server at a random moment
> - finally we check if the server has received the same data as the clients
> have sent.
>
 How does the server receives the data from a particular client:
- Does it receive the data from a single client in different threads? And
if so, does it use a strand for the receiving?
- Or maybe the server distributes the client sessions to separate
executors/io_contexts/threads and thus no synchronization/strands are
needed for the receiving?

>
> With boost versions up to 1.81.0 the test passes OK. But with boost
> version 1.82.0 we observe wrong order of the data stored
> by the server. To illustrate it roughly:
> Client sends:  0,1,2
> Server stores: 0,2,1 (0 is OK, Next we should have 1, but we get 2).
> Note: the real test data is hundreds of bytes long, not single digits.
> Note: the test seems to have issues, but on the particular machine, the
> behavior is consistent:
>       test is OK with boost 1.81.0 and NOK with boost 1.82.0
>
Do you mean that a single client sends 0,1,2 sequences of data or multiple
clients do that? (I understand that it's just an example of the real data).

>
> I suspect the problem has something to do with the "on_immediate()"
> extension, introduced in boost 1.82.0.
> Somehow it speeds up the client threads execution and changes the order of
> the sent data.
> I failed to find any similar problems, reported in internet (git, boost
> forums, etc)
>
> I have enabled BOOST_ASIO_ENABLE_HANDLER_TRACKING and, if I get the log
> right, client threads are executed faster.
> I have attached the handler tracking logs for boost versions 1.81.0 and
> 1.82.0.
>
> My question is how to keep the old code behavior (pre 1.82.0) with later
> versions?
> Is there any way to disable the "on_immediate()" functionality?
> Are there any guidelines for using later versions of boost ASIO (1.82.0
> and later)?
>
>
> Providing a simplified example test is hard, as the code-base is quite
> large.
> I will try to make something up, but this will take time.
>
> Thank you!
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> https://lists.boost.org/mailman/listinfo.cgi/boost-users
>