Kernel Release Notes

Kernel 2.2.1

Known problems

• If an error occurs when accessing a file, the file process dies, and any further attempts to access the file may cause the caller to hang.
  Own Id: OTP-1400
  Aux Id: OTP-1034
• Using gen_tcp:send on a closed socket causes the process to hang.
  Own Id: OTP-2714
  Aux Id: seq 1122
• If more than 1024 bytes of text (more than 256 in release R4) are pasted into the shell, and this text consists of more than one expression sequence (each ending with a period), text after the first 1024 bytes may be lost.
  Own Id: OTP-3041

Fixed errors and malfunctions

• global locks do now keep track of all pids that share the same lock, i.e after two set_lock and one del_lock the lock is still set.
  Own Id: OTP-1849
• Global may have exited if bursty nodeup/nodedowns was received to a node. This is solved now.
  Own Id: OTP-2766
  Aux Id: otp-2728, otp-2928
• Changes of the kernel configuration parameter 'distributed' are now taken care of at release upgrade. Kernel will however not automatically move applications to the nodes with highest priority; this must be done manually after the release upgrade is finished (use application:takeover/2).
  Own Id: OTP-2830
• If a transient application exited with reason normal application_controller crashed; this malfunction is now corrected.
  Own Id: OTP-2955
  Aux Id: seq1445
• If a system is started and a permanent application has erroneous environment parameters, the system should crash. This is the behaviour now, before the system only printed an error report. The system will only crash if the application is started from a boot script genrated by calling systools:make_script/1/2 If application:start/1/2 is called the behaviour is as before.
  Note: affects the result of the systools:make_script/1/2. systools:make_script generates now a call to application:start_boot/2 instead of as prevoiusly a call to application:start/2.
  Own Id: OTP-3002
• applicaition:get_application(module_name) returned 'undefined' if the module_name was defined as {module_name, Vsn} in the .app-file
  Own Id: OTP-3081
  Aux Id: Seq 1618
• The possible InternalStatus stopping was missing in the documentation for init:get_status/0.
  Own Id: OTP-3096
  Aux Id: Seq 1672
• when opening an externally formatted disk log the header was not written to the files.
  Own Id: OTP-3118
• application:permit can now handle also applications which are only loaded (but not started).
  Own Id: OTP-3119
• When reading a wrap log and for some reason a file was missing an error was given and it was not possible to read further. Now a missing file will result only in an error log message and it is possible to continue reading the log.
  Own Id: OTP-3136
  Aux Id: OTP-3137
• It is now possible to open an existing wrap log without giving the size parameter. The last given values will be used as default values.
  Own Id: OTP-3147

Improvements and new features

• It is now possible to change the size of an open disk log. For a halt log it is always possible to increase the size, but it is not possible to decrease the size to be less than the current size of the file. For a wrap log it is always possible to increase both the size and number of files. If the max files is decreased the redundant files will be removed next time the log wraps. If the size of the files is decreased the change will not affect the logs already full. If the log size is decreased for instance to save space, the function inc_wrap_log/1 can be used to force the log to wrap.
  Own Id: OTP-2999
  Aux Id: OTP-2989,OTP-2990,seq 1499
• It is possible to force the disk_log to change to next wrap log file by calling the new function disk_log:inc_wrap_log(Log). This makes the current file to be closed and the next index file is opened.
  Own Id: OTP-3078
  Aux Id: Seq 1607
• The undocumented and not recommended BIFs erlang:spawn/2 and erlang:spawn_link/2 will disappear in OTP R6, to be replaced with a more consistent set of BIFs for spawning processes from funs.
  Own Id: OTP-3141
  Aux Id: OTP-3121

Kernel 2.2

Fixed errors and malfunctions

• net_adm:names did not always return the correct result when epmd on the own host was called on Windows or Linux. This is now corrected.
  Own Id: OTP-2851
  Aux Id: OTP-2840
• Some BIFs e.g append could during certain circumstances consume huge amounts of memory (causing the Erlang node to crash) before the garbage collector was invoked to free the unused memory. This is now corrected.
  Own Id: OTP-2865
  Aux Id: Seq 1337
• When a heart command is set with heart:set_cmd(Command) the length is miscalculated which results in 2 garbage characters at the end of the command. This can cause the heart command to fail if the garbage characters are other chars then SPACE or NULL. This is now corrected.
  Own Id: OTP-2903
  Aux Id: Seq 1372
• I thought I already had written the release note for thisx
  Own Id: OTP-2911
  Aux Id: Seq 1384
• Previously gen_tcp:accept erroneously could return {error,normal}. This is now corrected.
  Own Id: OTP-2954
  Aux Id: Seq 1374, OTP-2904
• A request to start a distributed application, which already was started, caused that the application controller hanged. This malfunction is now corrected.
  Own Id: OTP-2967
  Aux Id: Seq 1474
• Two processes starting the same application on the same node at the same time actually started the application twice.
  Now the systems keeps track of all the start requests and starts the application only once. The result of the start is returned to all requesters.
  Own Id: OTP-2973
  Aux Id: Seq 1461
• A local application would not start when its permission was set to true if it was initially started with permission set to false.
  Own Id: OTP-2974
• The error returns from the functions in the rpc module were not consistent: if {badrpc, {'EXIT', Reason}} was reported for remote nodes, only {badrpc, Reason} was reported for the local node. Now, {badrpc, {'EXIT', Reason}} is reported in both cases.
  (*** POTENTIAL INCOMPATIBILITY ***)
  Own Id: OTP-3007
  Aux Id: OTP-2875
• net_adm:localhost/0 is corrected to not append a "." to the hostname if the domain is not set (i.e when the domain is the empty string).
  Own Id: OTP-3013
  Aux Id: Seq 1533
• On Unix, if there were no current working directory for an Erlang node (if another Unix process has deleted the directory), the commands c:pwd/0, m/0, and m/1 would crasch. The pwd has been corrected to print "Cannot determine current directory" if there are no current directory, and the other commands do not attempt to convert absolute pathnames to relative pathnames as they usually do.
  Own Id: OTP-3015
  Aux Id: Seq 1537
• When starting the emulator with the -noshell switch, a "^R" marker was printed if reading and writing on the console was mixed. This marker is no longer printed.
  Own Id: OTP-3085
  Aux Id: Seq 1629

Improvements and new features

• Functions have been added to the file module to handle links. The read_link_info/1 reads information about a symbolic link, and the read_link/1 function returns what a symbolic link is actually pointing to. The make_link function creates a new hard link, and the make_symlink function creates a new symbolic link.
  Own Id: OTP-1385
  Aux Id: OTP-3008
• It is now possible to reconfigure global groups. The parameter name is changed from node_groups to global_groups.
  Own Id: OTP-2497
  Aux Id: OTP-1559
• gen_udp:recv/3 has been added, in analogy with gen_tcp:recv/3, and gen_udp:recv/[2,3] are now documented.
  Own Id: OTP-2645
• Allowed number of files in a wrap log is increased from 255 to 65000.
  Own Id: OTP-2748
  Aux Id: seq 1204
• gen_tcp:connect/[3,4] take the same options as gen_udp:open/[1,2], in particular the binary option. This is not new in R5, but was left out of the documentation.
  Own Id: OTP-2814
  Aux Id: Seq 1250
• The syntax of Erlang tokens has been extended to allow the use of the full ISO-8859-1 (Latin-1) character set. This is noticeable in the following ways: all the Latin-1 printable characters can be used and are shown without the escape backslash convention; atoms and variables can use all Latin-1 letters.
  Own Id: OTP-2985
• The disk_log wrote a header every time a log file was opened, now the header is only written once in each file.
  Own Id: OTP-3014
  Aux Id: Seq 1534
• A new open mode, append, has been added to the file:open/2 function.
  Own Id: OTP-3067