Pipe any thing to curl's stdin to be http requested, but "flush" curl's stdin every Nth request

curl

## cUrl, used with "-K -", reads the config from the stdin, but waits for stdin's EOF before executing any HTTP requests 
## See : http://comments.gmane.org/gmane.comp.web.curl.general/15001

## Using the split's filter options allows starting and piping a stream to a new curl's stdin every N requests
## A same connexion can be kept alive for those N requests, making perfs much much better 

## TODO : Find a way to parallelise several curl in a "xargs -P" way

## Example : (the for loop is there to simulate some real stream, and to demonstrate the curl's required format)

N=1000
for i in {1..10000}; do
  echo -en '
    --next
    --url "es1:9200/test/node'${i}'?ttl=30"
    --header "Content-Type: application/json"
    --data {"test":true}
    \0
  ';
done \
  | split -t '\0' -l ${N} --filter='curl -sSK -'
  
## You can even add some niceties and get some progress bar and a final report 

N=1000
tStamp=$(date +%s)
for i in {1..10000}; do
  echo -en '
    --next
    --url "es1:8084/test/node'${i}'?ttl=30"
    --header "Content-Type: application/json"
    --data {"test":true}
    --output /dev/null
    --write-out "%{http_code}\\n"
    \0
  ';
done \
  | split -u -t '\0' -l ${N} --filter='curl -sSK -' \
  | pv -r -l \
  | awk -v tStamp=${tStamp} '
    {
      rc[$0]++;
      rc["total"]++;
    }
    END{
      elapse = systime() - tStamp;
      elapse = (elapse == 0) ? 1 : elapse;
      print "-------------\nReport :";
      print "\telapse : " elapse " Sec";
      for(i in rc) {
        print "\thttp_" i ":\t" rc[i] " | throughput: " rc[i] / elapse " Req/Sec";
      };
    }
  '

## The split filter option is not that old, and could be unavailable on you system 
## To build a fresh version of split from source : 

#mkdir -p /tmp/coreutils
#cd /tmp/coreutils
#wget http://ftp.gnu.org/gnu/coreutils/coreutils-8.25.tar.xz
#yum install xz -y
#xz -d coreutils-8.25.tar.xz
#tar xvf coreutils-8.25.tar
#cd coreutils-8.25
#mkdir -p /tmp/coreutils/coreutils-8.25/output
#./configure --prefix /tmp/coreutils/coreutils-8.25/output
#make
#make install
#alias split="/tmp/coreutils/coreutils-8.25/output/bin/split"