ElasticSearch (search_context_missing_exception) with Search::ElasticSearch::Scroll - perl

Question

I'm using Search::Elasticsearch and Search::Elasticsearch::Scroll for search and scroll into my elasticsearch server.
In scrolling process, for some querys, I'm seeing the next errors while I'm scrolling the search results:
2016/03/22 11:03:38 - 265885 FATAL: [Daemon.pm][8221]: Something gone wrong, error $VAR1 = bless( {
'msg' => '[Missing] ** [http://localhost:9200]-[404] Not Found, called from sub Search::Elasticsearch::Scroll::next at searcher.pl line 92. With vars: {\'body\' => {\'hits\' => {\'hits\' => [],\'max_score\' => \'0\',\'total\' => 5215},\'timed_out\' => bless( do{\\(my $o = 0)}, \'JSON::XS::Boolean\' ),\'_shards\' => {\'failures\' => [{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [4920053]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [5051485]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [4920059]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [5051496]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1},{\'index\' => undef,\'reason\' => {\'reason\' => \'No search context found for id [5051500]\',\'type\' => \'search_context_missing_exception\'},\'shard\' => -1}],\'failed\' => 5,\'successful\' => 0,\'total\' => 5},\'_scroll_id\' => \'c2NhbjswOzE7dG90YWxfaGl0czo1MjE1Ow==\',\'took\' => 2},\'request\' => {\'serialize\' => \'std\',\'path\' => \'/_search/scroll\',\'ignore\' => [],\'mime_type\' => \'application/json\',\'body\' => \'c2Nhbjs1OzQ5MjAwNTM6bHExbENzRDVReEc0OV9UMUgzd3Vkdzs1MDUxNDg1OnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7NDkyMDA1OTpscTFsQ3NENVF4RzQ5X1QxSDN3dWR3OzUwNTE0OTY6cmtDeWxSREpUdHFFZFZ5RGg5MHhZUTs1MDUxNTAwOnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7MTt0b3RhbF9oaXRzOjUyMTU7\',\'qs\' => {\'scroll\' => \'1m\'},\'method\' => \'GET\'},\'status_code\' => 404}
',
'stack' => [
[
'searcher.pl',
92,
'Search::Elasticsearch::Scroll::next'
]
],
'text' => '[http://localhost:9200]-[404] Not Found',
'vars' => {
'body' => {
'hits' => {
'hits' => [],
'max_score' => '0',
'total' => 5215
},
'timed_out' => bless( do{\(my $o = 0)}, 'JSON::XS::Boolean' ),
'_shards' => {
'failures' => [
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [4920053]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [5051485]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [4920059]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [5051496]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
},
{
'index' => undef,
'reason' => {
'reason' => 'No search context found for id [5051500]',
'type' => 'search_context_missing_exception'
},
'shard' => -1
}
],
'failed' => 5,
'successful' => 0,
'total' => 5
},
'_scroll_id' => 'c2NhbjswOzE7dG90YWxfaGl0czo1MjE1Ow==',
'took' => 2
},
'request' => {
'serialize' => 'std',
'path' => '/_search/scroll',
'ignore' => [],
'mime_type' => 'application/json',
'body' => 'c2Nhbjs1OzQ5MjAwNTM6bHExbENzRDVReEc0OV9UMUgzd3Vkdzs1MDUxNDg1OnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7NDkyMDA1OTpscTFsQ3NENVF4RzQ5X1QxSDN3dWR3OzUwNTE0OTY6cmtDeWxSREpUdHFFZFZ5RGg5MHhZUTs1MDUxNTAwOnJrQ3lsUkRKVHRxRWRWeURoOTB4WVE7MTt0b3RhbF9oaXRzOjUyMTU7',
'qs' => {
'scroll' => '1m'
},
'method' => 'GET'
},
'status_code' => 404
},
'type' => 'Missing'
}, 'Search::Elasticsearch::Error::Missing' );
The code I'm using is the next one (simplified) :
# Retrieve scroll
my $scroll = $self->getScrollBySignature($item);
# Retrieve all affected documents ids
while (my #docs = $scroll->next(500)) {
# Do stuff with #docs
}
The function getScrollBySignature have the next code in order to call to elasticSearch
my $scroll = $self->{ELASTIC}->scroll_helper(
index => $self->{INDEXES},
search_type => 'scan',
ignore_unavailable => 1,
body => {
size => $self->{PAGINATION},
query => {
filtered => {
filter => {
bool => {
must => [{term => {signature_id => $item->{profileId}}}, {terms => {channel_type_id => $type}}]
}
}
}
}
}
);
As you can see, I'm doing the scroll without passing scroll parameter then as documentation says, the time that scroll is alive is 1 min.
The elasticSearch is a cluster of 3 servers, and the query that ends with that error retrieves a bit more than 5000 docs.
My first solution was to update the life time for scroll to 5 minutes and the error didn't appear.
The question is, as I understand every time I'm calling $scroll->next() the life time off scroll affected is upgraded 1m more, then how is possible to receive those context related errors?
I'm doing something in a bad manner?
Thank you all.

Answer 1

The first thing that comes to mind is that the timer is not updated. Have you checked this? You can do a query every 10 seconds for example and see if at the 6th query it gives you the error ...

Answer 2

Well, a good rule of thumb is inside a ->next() block, don't stay by iteration more than time that you've configured in scroll.
Between each call of ->next() you cannot stay more than that time configured. If you stay more, the scroll may be not be there and the error earch_context_missing_exception will appear.
My solution for this problem was inside next block only store data into array/hash structure and once the scroll process ended work with all data.
The solution of the question example:
# Retrieve scroll
my $scroll = $self->getScrollBySignature($item);
# Retrieve all affected documents ids
my #allDocs;
while (my #docs = $scroll->next(500)) {
push #allDocs, map {$_->{_id}} #docs
}
foreach (#allDocs) {
# Do stuff with doc
}