If you're using jConnect over TDS, the server modifies connection options under-the-covers to try to mimic ASE behaviour as much as possible. One of the settings that is modified is the connection's isolation level, which is set to 1. Unless you do something explicit in your application to reset the isolation level back to 0, you're running at 1 and can hence block on write locks.

That said, there are minor differences between v8 and v12 with respect to locking, due to changes in the underlying execution model in the server.

As you are using jConnect (instead of the SQL Anywhere JDBC driver): Do you set the isolation level explicitly to 0? What does

select connection_property('isolation_level')

return?

AFAIK, jConnect uses special defaults values when connecting, among others a default isolation level of 1 - cf. the docs.

Besides that, I would agree with you on the behaviour you expect.

Did you change the way you are connecting at the same time as upgrading? e.g., from ODBC to JDBC

It's not really under the covers, and it is not magic...

If connection_property('CommProtocol') used to be 'CmdSeq' (which is good) and now it is = 'TDS' (bad), the sp_tsql_environment stored procedure may be doing you great harm... IMO that stored procedure is evil evil evil evil evil (that's five evil's, the maximum possible score).

Here's what happens by default, if you haven't changed anything else:

The default setting

SET OPTION PUBLIC.login_procedure = 'sp_login_environment';

causes the following stored procedure to be called for every connection:

create procedure dbo.sp_login_environment()
begin
  if connection_property('CommProtocol') = 'TDS' then
    call dbo.sp_tsql_environment()
  end if
end

If 'TDS' is being used then the following procedure is called:

create procedure dbo.sp_tsql_environment()
begin
  if db_property('IQStore') = 'OFF' then
    -- ASA datastore
    set temporary option Automatic_timestamp = 'ON'
  end if;
  set temporary option Ansinull = 'OFF';
  set temporary option Tsql_variables = 'ON';
  set temporary option Ansi_blanks = 'ON';
  set temporary option Tsql_hex_constant = 'ON';
  set temporary option Chained = 'OFF';
  set temporary option Quoted_identifier = 'OFF';
  set temporary option Allow_nulls_by_default = 'OFF';
  set temporary option On_tsql_error = 'CONTINUE';
  set temporary option Float_as_double = 'ON';
  set temporary option Isolation_level = '1';
  set temporary option Date_format = 'YYYY-MM-DD';
  set temporary option Timestamp_format = 'YYYY-MM-DD HH:NN:SS.SSS';
  set temporary option Time_format = 'HH:NN:SS.SSS';
  set temporary option Date_order = 'MDY';
  set temporary option Escape_character = 'OFF';
  set temporary option Close_on_endtrans = 'OFF'
end

The easiest way to stop all this foolishness is to turn it off... remember that NONE OF THAT CRAP is done for 'CmdSeq' connections, and if you want the same behavior now then the following will be just fine for you... just because you are using TDS doesn't mean your application is SUPPOSED to work incorrectly:

SET OPTION PUBLIC.login_procedure = NULL; 

Another option is to slightly modify the evil-doer to JUST fix the stupid setting for isolation level:

alter procedure dbo.sp_tsql_environment()
begin
  if db_property('IQStore') = 'OFF' then
    -- ASA datastore
    set temporary option Automatic_timestamp = 'ON'
  end if;
  set temporary option Ansinull = 'OFF';
  set temporary option Tsql_variables = 'ON';
  set temporary option Ansi_blanks = 'ON';
  set temporary option Tsql_hex_constant = 'ON';
  set temporary option Chained = 'OFF';
  set temporary option Quoted_identifier = 'OFF';
  set temporary option Allow_nulls_by_default = 'OFF';
  set temporary option On_tsql_error = 'CONTINUE';
  set temporary option Float_as_double = 'ON';
  set temporary option Isolation_level = '0';
  set temporary option Date_format = 'YYYY-MM-DD';
  set temporary option Timestamp_format = 'YYYY-MM-DD HH:NN:SS.SSS';
  set temporary option Time_format = 'HH:NN:SS.SSS';
  set temporary option Date_order = 'MDY';
  set temporary option Escape_character = 'OFF';
  set temporary option Close_on_endtrans = 'OFF'
end

Some people write a different procedure to replace sp_login_environment, and change the value of login_procedure... a bunch of make-work if you ask me but I'll show you how if you want :)