Remove pretty printing from register cache

[jlennox]

We're hitting some sort of memory issue with register's caching. A workaround is to remove the pretty printing.

When I deleted node_modules/.cache/@babel/register/.babel.7.13.10.development.json

• then run with JSON.stringify(data, null, " "); the re-created file is 152,577kb.
• then run with JSON.stringify(data); the re-created file is 109,352kb.

Since there's no reason to store a cache file pretty printed, we can reduce the memory pressure by ~30% by not doing that.

Q	A
Fixed Issues?
Patch: Bug Fix?	Reduces occurrences of /issues/5667
Major: Breaking Change?	No
Minor: New Feature?	No
Tests Added + Pass?	No
Documentation PR Link
Any Dependency Changes?	No
License	MIT

The crash report I'm seeing is:

1% setup initializeStacktrace:
   ptr1=00000025696C0541
    ptr2=0000000000000000
    ptr3=0000000000000000
    ptr4=0000000000000000
    failure_message_object=0000000FA9B86EE0

==== JS stack trace =========================================

    0: ExitFrame [pc: 00007FF741B2CF5D]
    1: StubFrame [pc: 00007FF741BA3810]
Security context: 0x008aebb008d1 <JSObject>
    2: save(aka save) [000002E34C3A6371] [BLAHBLAH\node_modules\@babel\register\lib\cache.js:52] [bytecode=000002D36A7A9BC9 offset=68](this=0x0025696c0471 <undefined>)
    3: processTicksAndRejections [0000018D77E422E1] [internal/process/task_queues.js:77] [bytecode=000002D36A7A8FA9 offset=73](this=0x018d77e41ed1 <process map = 00000229CDCF3931>)
    4: InternalFrame [pc: 00007FF741AC0DDE]
    5: EntryFrame [pc: 00007FF741AC09CC]

==== Details ================================================

[0]: ExitFrame [pc: 00007FF741B2CF5D]
[1]: StubFrame [pc: 00007FF741BA3810]
[2]: save(aka save) [000002E34C3A6371] [BLAHBLAH\node_modules\@babel\register\lib\cache.js:52] [bytecode=000002D36A7A9BC9 offset=68](this=0x0025696c0471 <undefined>) {
  // expression stack (top to bottom)
  [06] : 0x00c4c5f0cd19 <String[#2]:   >
  [05] : 0x0025696c01b1 <null>
  [04] : 0x03b73e642d79 <Object map = 00000229CDCC4BF1>
  [03] : 0x0025696c0541 <the_hole>
  [02] : 0x02e34c3a8221 <FunctionContext[11]>
  [01] : 0x02c30bd18721 <CatchContext[3]>
  [00] : 0x03b59f44b141 <String[#2]: {}>
--------- s o u r c e   c o d e ---------
function save() {\x0a  if (isCacheDisabled()) return;\x0a  let serialised = "{}";\x0a\x0a  try {\x0a    serialised = JSON.stringify(data, null, "  ");\x0a  } catch (err) {\x0a    if (err.message === "Invalid string length") {\x0a      e
rr.message = "Cache too large so it's been cleared.";\x0a      console.error(err.stack);\x0a    } else {\x0a  ...

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/51353/

[jlennox]

@nicolo-ribaudo Is there anything else I need to do prior to merge? Sorry -- I'm not familiar with the process here.

[jridgewell]

Another idea here: We currently set sourceMaps to "both", which creates an map object and embeds an inline sourceMappingUrl=${JSON.stringify(map)} in the code string. I'm not certain we need the object, we can parse it out of the code as needed (if we even need it, source-map-support supports just the inline comment without us doing anything)

[nicolo-ribaudo]

I'm merging this for now, but I'm definitely open to further improvements.