Error or not error? What does this unreadable line in Maven install output mean?

Question

The Maven install output in Eclipse writes several of such lines:

[ERROR]  50% 21/31 build modules 52% 22/31 build .... 

I am putting here only part of one of these lines, they are extremely long. You can see the whole output on the Google Drive. Look out for [ERROR] there.

I don't like to see these error messages not knowing what they are about. What if they signalize on something really bad? Or simply bad? Or they are merely Maven's Halloween jokes? I am afraid not.

All projects of the workspace seem to be installed OK

[INFO] ca-sp .............................................. SUCCESS [ 24.287 s]
[INFO] ca-cm .............................................. SUCCESS [ 21.186 s]
[INFO] ca ................................................. SUCCESS [ 20.438 s]
[INFO] ca-tests ........................................... SUCCESS [  1.340 s]

But

after that, at the end, I see:

FATAL ERROR in native method: JDWP Can't allocate jvmti memory, jvmtiError=JVMTI_ERROR_INVALID_ENVIRONMENT(116)
FATAL ERROR in native method: JDWP on getting class status, jvmtiError=JVMTI_ERROR_WRONG_PHASE(112)

The next lines are in red:

JDWP exit error JVMTI_ERROR_WRONG_PHASE(112): on getting class status [util.c:1285]
JDWP exit error JVMTI_ERROR_INVALID_ENVIRONMENT(116): Can't allocate jvmti memory [util.c:1799]
ERROR: JDWP unable to dispose of JVMTI environment: JVMTI_ERROR_INVALID_ENVIRONMENT(116)

These fatal errors are known as eclipse bugs here. I am afraid, you won't help me with them. When the maven makes the install, these end errors can appear or not, with the probability about 2/3. But those strange unreadable [error] lines appear always. I hope, understanding them could save me from the errors coming at the end.

Eclipse:
Version: Oxygen.1a Release (4.7.1a)
Build id: 20171005-1200

Java:
jdk-8u152-windows-x64.exe

Answer 1

Long log lines starting like

[ERROR] ???????????? 0% compile?????????????????????? 10% 0/1 build modules

are most probably progress indicator logs which have been set logged with wrong level (and wrong way?) in development phase and never changed to appropriate level when releasing.

Hardly developer has thought that it is actually an error that module gets build but has forgotten to change the level to [DEBUG/INFO].

Character ? marks non printable character which is always 0x08 = BACKSPACE. Why there are such chars and why all this stuff is in a single line is a mystery. Maybe someone needs this kind of output for some analysis?

If you remove those chars and and add line feeds to appropriate places you will get stuff like (my guess in in comments not necessarily correct):

[ERROR] 0% compile
10% 0/1 build modules    // build for module 1 started
70% 1/1 build modules    // build for module 1 near to finish
40% 1/2 build modules    // build for module 2 started
70% 2/2 build modules    // build for module 2 near to finish
50% 2/3 build modules    // build for module 3 started (and so on)
70% 3/3 build modules
54% 3/4 build modules

Interesting detail is also that there is exactly the same amount of backspaces before each readable part of log, for example (i have added line feeds but spaces are in text):

????????????
  0% compile               // two spaces before text
??????????????????????
 10% 0/1 build modules     // one space before text

Coincidence?