[ruby_memcheck] failures spotted in CI

[flavorjones]

Seen at https://github.com/sparklemotion/nokogiri/runs/4549544439?check_suite_focus=true#step:7:4016

16,720 (336 direct, 16,384 indirect) bytes in 1 blocks are definitely lost in loss record 37,802 of 38,098
  calloc (vg_replace_malloc.c:760)
  calloc1 (gc.c:1583)
  heap_page_allocate (gc.c:1812)
  heap_page_create (gc.c:1910)
  heap_assign_page (gc.c:1935)
  heap_increment (gc.c:2018)
  heap_prepare (gc.c:2037)
  heap_next_freepage (gc.c:2189)
  ractor_cache_slots (gc.c:2208)
  newobj_slowpath (gc.c:2254)
  newobj_slowpath_wb_protected (gc.c:2273)
  newobj_of0 (gc.c:2312)
  newobj_of (gc.c:2322)
  rb_wb_protected_newobj_of (gc.c:2344)
  str_alloc (string.c:784)
  str_new0 (string.c:806)
  rb_enc_str_new (string.c:858)
 *rb_xml_node_content (xml_node.c:749)
  ...
{
  insert_a_suppression_name_here
  Memcheck:Leak
  fun:calloc
  fun:calloc1
  fun:heap_page_allocate
  fun:heap_page_create
  fun:heap_assign_page
  fun:heap_increment
  fun:heap_prepare
  fun:heap_next_freepage
  fun:ractor_cache_slots
  fun:newobj_slowpath
  fun:newobj_slowpath_wb_protected
  fun:newobj_of0
  fun:newobj_of
  fun:rb_wb_protected_newobj_of
  fun:str_alloc
  fun:str_new0
  fun:rb_enc_str_new
  fun:rb_xml_node_content
  ...
}

I could add this to the memcheck todo list (in /suppressions/) but I want to see how commonly this pops up to see if we can learn something first.

[flavorjones]

Another seen at

• https://github.com/sparklemotion/nokogiri/runs/7287036089?check_suite_focus=true
• https://github.com/sparklemotion/nokogiri/runs/7471552599?check_suite_focus=true

37 bytes in 1 blocks are definitely lost in loss record 14,158 of 38,756
  malloc (vg_replace_malloc.c:307)
  objspace_xmalloc0 (gc.c:11445)
  str_new0 (string.c:900)
  rb_enc_str_new (string.c:946)
 *Nokogiri_wrap_xml_syntax_error (xml_syntax_error.c:53)
 *Nokogiri_error_array_pusher (xml_syntax_error.c:33)
 *__xmlRaiseError (error.c:604)
 *htmlParseErr (HTMLparser.c:117)
 *htmlParseComment (HTMLparser.c:3519)
 *htmlParseContentInternal (HTMLparser.c:4819)
 *htmlParseDocument (HTMLparser.c:4992)
 *htmlDoRead (HTMLparser.c:6912)
 *rb_html_document_s_read_memory (html4_document.c:111)
  ...
{
  insert_a_suppression_name_here
  Memcheck:Leak
  fun:malloc
  fun:objspace_xmalloc0
  fun:str_new0
  fun:rb_enc_str_new
  fun:Nokogiri_wrap_xml_syntax_error
  fun:Nokogiri_error_array_pusher
  fun:__xmlRaiseError
  fun:htmlParseErr
  fun:htmlParseComment
  fun:htmlParseContentInternal
  fun:htmlParseDocument
  fun:htmlDoRead
  fun:rb_html_document_s_read_memory
  ...
}

[flavorjones]

I've opened https://github.com/Shopify/ruby_memcheck/issues/6 to ignore stack_chunk_alloc-related stacks which have showed up in:

• https://github.com/sparklemotion/nokogiri/runs/7474777076?check_suite_focus=true
• https://github.com/sparklemotion/nokogiri/runs/7457816991?check_suite_focus=true
• https://github.com/sparklemotion/nokogiri/runs/7282476570?check_suite_focus=true
• https://github.com/sparklemotion/nokogiri/runs/7310948711?check_suite_focus=true
• https://github.com/sparklemotion/nokogiri/runs/7287062715?check_suite_focus=true

and all start with

#   malloc (vg_replace_malloc.c:307)
#   stack_chunk_alloc (gc.c:5917)
#   push_mark_stack_chunk (gc.c:5980)
#   push_mark_stack (gc.c:6038)
#   gc_grey (gc.c:6665)

[flavorjones]

Here's another one that might be ruby internals and not the C extension code?

• https://github.com/sparklemotion/nokogiri/runs/7282108248?check_suite_focus=true
• https://github.com/sparklemotion/nokogiri/runs/7273451879?check_suite_focus=true

# 39,848 bytes in 1 blocks are definitely lost in loss record 38,889 of 38,956
#   realloc (vg_replace_malloc.c:834)
#   objspace_xrealloc.constprop.0 (gc.c:11516)
#   ary_heap_realloc (array.c:381)
#   ary_resize_capa (array.c:461)
#   ary_double_capa (array.c:507)
#   ary_ensure_room_for_push (array.c:654)
#   rb_ary_push (array.c:1311)
#  *noko_xml_node_wrap (xml_node.c:2075)
#  *noko_xml_node_attrs (xml_node.c:2094)
{
  insert_a_suppression_name_here
  Memcheck:Leak
  fun:realloc
  fun:objspace_xrealloc.constprop.0
  fun:ary_heap_realloc
  fun:ary_resize_capa
  fun:ary_double_capa
  fun:ary_ensure_room_for_push
  fun:rb_ary_push
  fun:noko_xml_node_wrap
  fun:noko_xml_node_attrs
  ...
}

which I suppressed in https://github.com/sparklemotion/nokogiri/commit/a0360803740e5c85767ace75563bb3a3b33d1963